Cirq v0.7.0

Major usability changes:

• Added new gates: PhasedXZGate, WaitGate, givens, ISwapRotation, IdentityGate, MatrixGate
• cirq.Rx cirq.Ry cirq.Rz cirq.MS changing to cirq.rx, cirq.ry, cirq.rz cirq.ms
• Added commutes protocol
• Added import capability from Quirk
• Improved JSON serialization support
• Many speed up and performance improvements.
• Added Sycamore Devices and optimizers to cirq.google
• Added many engine-related improvements to cirq.google
• Deleted Schedules

New protocols:

• cirq.apply_mixture
• cirq.definitely_commutes

New top level objects:

• cirq.givens
• cirq.quirk_json_to_circuit
• cirq.quirk_url_to_circuit
• cirq.estimate_single_qubit_readout_errors
• cirq.ISwapRotation
• cirq.MatrixGate
• cirq.PAULI_GATE_LIKE
• cirq.PhasedXZGate
• cirq.riswap
• cirq.rx
• cirq.ry
• cirq.rz
• cirq.decompose_two_qubit_interaction_into_four_fsim_gates_via_b
• cirq.STATE_VECTOR_LIKE

Full change list:

f56e6fb Add test_json_data files to package
266491a Create add method for Moment (#2665)
de6ca2d Better decomposition of SWAP into ISWAP ** 0.5 (#2682)
575ae93 Make grid_qubits addable (#2681)
58741a1 Add gate duration for xyz gate (#2680)
91e919a Delete cirq.api.google (#2667)
3469e5c (t2_experiments) Change symbols in phased_iswap_test (#2672)
f306544 Remove code for GCS locations since they are no longer used. (#2668)
02ee285 Add PhasedXZ gate to standard single qubit (de)serializers (#2661)
86e059a Add device_specification to engine code (#2640)
f7f224c Fix typo in SerializableDevice print out (#2660)
2c8914b Quantum Volume: Add the ability to specify the device graph to compile the model circuit onto (#2645)
7fb1a49 Add documentation for cirq.google devices (#2636)
ed6188b Add commutes protocol (#1853)
1017bae Add __tracebackhide__ = True to several test methods (#2653)
1309e99 Add optional qubit_set property to cirq.Device (#2605)
5968ccd Adds basic PhasedISwapPow gate to Sycamore decomposition function (#2629)
933329b Fix automerge script not seeing PRs on second page (#2654)
b928a87 Fix instability in _decompose_interaction_into_two_b_gates_ignoring_single_qubit_ops (#2609)
9a5a09e Fix serialization breakage due to sympy.Rational now being a numbers.Number (#2655)
c78d345 Add optimized_for_gmon to optimize circuits for Sycamore devices (#2627)
58d7722 Fix documentation and key error in calibration (#2633)
da513ac adds max_num_empty_steps parameter (#2631)
a038bd3 Mark test that sometimes fails on windows as xfail. (#2630)
3217135 Add pretty str for devices with grid qubits (#2616)
6d81ddb fix of router hanging #2282 (#2619)
2b88d34 Add optional tabulation to ConvertToSycamoreGates (#2615)
18a677d Update Alpha Disclaimer (#2611)
31b5436 Fix doc build by removing tensorflow dependency (#2610)
3a32a40 Add support for u1(lambda) gate (#2608)
42f9a37 Add explicit JSON resolver function in contrib (#2559)
07955c5 Detect duplicate mesurement keys. (#2604)
912c82a Add (de)serializer for PhasedXZGate (#2598)
7f8a4ff Add WaitGate to gate sets (#2601)
690b5f7 lengthen randomly generated program id (#2599)
993fa1e Delete things marked as deprecated-until-v0.7 (#2594)
6d986e6 Implement TrialResult JSON serialization (#2576)
55c1590 Make 'async def' tests work (#2583)
d963a02 Add Conversion optimizers to cirq.google init (#2593)
5dcab58 Fix parametrized -> parameterized typos (#2592)
2963285 Initial draft of ConvertToSycamore (#2516)
1c5084a Delete schedules (#2589)
8902820 Use warnings.warn for deprecation warnings (#2586)
ebd0b36 Add cirq.PhasedXPowZPowGate (#2566)
35c64e4 Move deprecated functions to deprecated docs section (#2585)
8beef6d Implement decompose_two_qubit_interaction_into_four_fsim_gates_via_b (#2574)
2920804 Rename Rx, Ry and Rz factories (#2580)
e76e36a Add Sycamore23 device (#2547)
2201aa0 AQT: Improve documentation, Add Z operations and rename AQTRemoteSimulator to AQTSamplerLocalSimulator (#2578)
8408f89 Fix pytest (#2584)
96f5f54 Make pytest-changed-files include api tests when an init file is changed (#2575)
e2446d4 Update ZPow.controlled specialization (#2572)
52b14db Fix radd losing device (#2451)
f14ed20 Support arbitrary exponents when exporting X/Y/ZPowGate to quirk url (#2513)
0682134 Zlib fix (#2573)
837c4e4 Initial draft for convert_to_sqrt_iswap (#2528)
d2f6344 Test gate being added multiple times. (#2560)
907f990 Add CircuitDiagramInfoArgs.format_real (#2569)
ad98557 Add Gate and Operation Guidelines dev docs (#2558)
a8c6ca2 Don't run async methods on other threads by default (#2562)
fab633d Fix several dozen relative type annotations (#2568)
4be5578 Make QuantumEngineSampler engine accessible through property (#2564)
c055eea Fix NoisySingleQubitReadoutSampler test class (#2563)
a90051e Turn off flaky build-protos check (#2571)
e904305 Define cirq.PAULI_GATE_LIKE (#2557)
dac7814 Add single qubit readout calibration (#2532)
bb0afb3 Fixes "Mention the difference between stable docs and latest docs." (#2549)
3a4d8a7 Add optional readout error correction to Quantum Volume (#2522)
26cadfb Implement JSON serialization for ParamResolver (#2555)
2bf4826 Add a special case for WaitGate in known devices (#2545)
8a8696f Fix MatrixGate pow and repr failing for non-qubit shapes (#2556)
a4025d1 Add developer doc explaining serialization (#2548)
781e84c make resolver repr evaluatable (#2554)
d0fc17e Rename givens rotation factory (#2519)
08df3b4 Rename Mølmer–Sørensen gate factory (#2518)
d6f65c2 Deprecate IdentityOperation obsoleted by IdentityGate (#2546)
23ce7ca Fix ParamResolver.param_dict type (#2550)
4ff38cf Refactor json_test's TEST_OBJECTS value into test data files (#2527)
6d5087c Rename iswap rotation (#2526)
7a15f02 Fix typo in contrib noise models (#2529)
c90644e Update path to Cirq_logo_color.png to make it appear in the README. (#2540)
0a5d3d4 Add check/pytest-changed-files-and-incremental-coverage (#2510)
a167b64 Client change google api (#2530)
d7927cb use RANDOM_STATE_LIKE in simulators (#2531)
15c142d Fix timings for Google devices (#2521)
390cc4a Use sum instead of einsum in QAOA example (#2507)
e2373e6 Make circuit rendering of PhasedISwapPowGate consistent with other gates (#2524)
d60cd5b identity operation -> gate property (#2515)
990be61 Simplify logic in PhasedXPowGate.circuit_diagram_info (#2525)
8f1c30a Add EigenGate.equal_up_to_global_phase (#1840)
5207900 Add support for serializing linear combinations of symbols (#2358)
95a14f2 Move quirk url importing out of contrib into interop (#2512)
a1ba3f9 Add 2-qubit gate decomp based on randomly filling the Weyl chamber to contrib (#2420)
07d8cd2 Specialize ZPow.controlled() to return CZPow for single qubit control. (#2402)
17d94cf Add docstrings for additional methods in #2480 (#2489)
aade1f3 Bump qiskit version used during qasm compatibility test (#2511)
1cdf343 Add support for importing custom gates in Quirk URLS (#2473)
ad490a7 Sycamore Device (#2485)
4670173 Add a documentation coverage test (#2498)
9b51176 Use @DataClass for cirq.google.[De]SerializingArg (#2494)
de2039d Increase prominence of doc links in readme (#2490)
0d08c9f Add logo(s) to the docs (#2491)
4a96e04 use python -m install everywhere in travis.yml (#2500)
94f7fd2 Allow creating new gatesets with added gates (#2458)
58a794f Define cirq.STATE_VECTOR_LIKE (#2376)
efb3afe Fix various protocols and result types not being exported (#2496)
5d9b9bb Various doc improvements in cirq/ops (#2495)
9becde4 Various doc fixes (#2497)
5c13dea ISwapRotation (#2488)
d7fefa8 PointOptimizerSummary option to avoid flattening (#2461)
9c0eb4c Associate docstrings with public constants (#2471)
0df878c Skip install step in misc check (#2483)
cd84155 CliffordTableau stabilizers and destabilizers methods return list of DensePauliString (#2480)
190c41f Extract generic MatrixGate, deprecate SingleQubit/TwoQubitMatrixGate (#2381)
93a9312 SVG circuit drawing updates (#2414)
1df0979 Speed up QAOA example (#2470)
0b48318 use testing assert function for more readable output (#2469)
b221c52 add atol parameter to tests (#2467)
be0615d Gate.controlled(0) return self (#2465)
1ec8a68 Speed up sampling in the case of measuring all qudits (#2463)
e54f0f1 Speed up density matrix sampling (#2462)
ef86e7a Speed up wavefunction sampling (#2460)
c266da8 Add random_state argument to linalg testing functions for seeded randomness (#2459)
d3cfe3f Implement JSON serialization for numpy dtypes (#2456)
dffd4ea Add WaitGate proto serialization (#2437)

Cirq v0.6.0

Major usability changes:

• Pandas. cirq.TrialResult now has a data property that returns results as a pandas.DataFrame, providing access to all of pandas' convenience methods for working with data.
• Qudit support. Added cirq.Qid.dimension and cirq.Operation._qid_shape_, as well as validation and simulator support.
• Packaging. Package variant cirq[contrib] with requirements for cirq.contrib. Unstable package cirq-unstable tracking master.
• Serialization. cirq.to_json and cirq.from_json methods can serialize (..almost) any cirq object.
• Deterministic randomness. Almost all methods with random behavior now take a seed or numpy.Random instance.
• Dropped support for python 2.7 and python 3.5.

New protocols:

• cirq.equal_up_to_global_phase / _equal_up_to_global_phase_
• cirq.qid_shape / _qid_shape_
• cirq.num_qubits / _num_qubits_

New top level objects:

• cirq.reset / cirq.ResetChannel
• cirq.WaitGate
• cirq.FSimGate
• cirq.GlobalPhasedOperation (the first operation with no qubits)
• cirq.ThreeQubitDiagonalGate
• cirq.DensePauliString
• cirq.MutableDensePauliString
• cirq.ArithmeticOperation (helper class for defining arithmetic operations)
• cirq.CCNOT = cirq.TOFFOLI alias
• cirq.CX = cirq.CNOT alias
• cirq.final_wavefunction
• cirq.subwavefunction
• cirq.wavefunction_partial_trace
• cirq.von_neumann_entropy
• cirq.apply_mixture
• cirq.one_hot
• cirq.axis_angle / cirq.AxisAngleDecomposition
• cirq.apply_unitaries
• cirq.approx_pauli_string_expectation
• cirq.flatten[/_with_params/_with_sweep] for inlining complicated sympy expressions into sweeps
• cirq.LinearCombinationOfOperations
• cirq.PauliSum
• cirq.SampleCollector
• cirq.op_gate_of_type
• cirq.op_gate_isinstance
• cirq.NOISE_MODEL_LIKE (flexible argument type for specifying noise models)
• cirq.PAULI_STRING_LIKE (flexible argument type for specifying pauli string arguments)
• cirq.CliffordSimulator, cirq.StabilizerStateChForm, cirq.CliffordTableau, cirq.CliffordState, cirq.CliffordTrialResult (all still rough)
• cirq.StabilizerStateChForm (still rough)
• cirq.SimulatesAmplitudes interface
• cirq.DepolarizingNoiseModel
• cirq.DepolarizingWithReadoutNoiseModel
• cirq.DepolarizingWithDampedReadoutNoiseModel
• cirq.pow_pauli_combination

New sub package objects:

• Added cirq.aqt package, which contains code to run cirq circuits on AQT's service.
• cirq.experiments.cross_entropy_benchmarking
• cirq.experiments.linear_xeb_fidelity
• cirq.experiments.log_xeb_fidelity
• cirq.experiments.log_xeb_fidelity_from_probabilities
• cirq.experiments.t1_decay
• cirq.experiments.xeb_fidelity
• cirq.contrib.qasm_import.circuit_from_qasm
• cirq.contrib.quirk.quirk_url_to_circuit
• cirq.contrib.quirk.quirk_json_to_circuit
• cirq.contrib.SVGCircuit
• cirq.contrib.circuit_to_svg

Other changes (partial list):

• Deprecated cirq.Circuit.from_ops in favor of cirq.Circuit.__init__
• Deprecated cirq.Circuit.to_unitary_matrix in favor of cirq.Circuit.unitary
• Deprecated cirq.Circuit.apply_unitary_effect_to_state in favor of cirq.Circuit.final_wavefunction
• Deleted cirq.google.XmonSimulator (use cirq.Simulator instead)
• cirq.approx_eq now recursively compares the items of iterables
• cirq.resolve_parameters now recursively resolves the items of iterables
• cirq.is_parameterized now recursively checks the items of iterables
• Added cirq.TrialResult.data method
• Added cirq.Sampler.sample method which returns a pandas.DataFrame
• cirq.ControlledGate.on now returns a cirq.ControlledOperation instead of a cirq.GateOperation
• simulator_state method on simulators is now private _simulator_state
• cirq.QasmUGate.__init__ now takes operations in the same order as defined in QASM spec
• cirq.PhasedXPowGate now longer auto-transforms itself into cirq.XPowGate or cirq.YPowGate at special phase angles
• Attempting to sample a circuit with no measurements now raises an error
• Fixed cirq.kak_canonicalize_vector not ensuring z>=0 when x=pi/4.
• Added cirq.PauliString.__add__/__sub__ methods
• Added cirq.PauliString.conjugated_by method
• Added cirq.PauliString.dense method
• Added cirq.X/Y/ZPowGate.__add__/__sub__ methods
• Generalized cirq.Circuit.__init__ to take any tree of moments/operations.
• Added cirq.PauliString._unitary_ methods
• Added DensityMatrixTrialResult.__str__
• Added a py.typed file telling mypy it can use cirq's inline type annotations
• Added cirq.PeriodicValue.__repr__
• cirq.GateOperation._pauli_expansion_
• Controlling by nothing (operation.controlled_by()) now has no effect instead of unnecessarily wrapping
• Added cirq.PauliString._decompose_
• Added cirq.GridQubit.square static method
• Added cirq.GridQubit.rect static method
• Added cirq.GridQubit.from_pic static method
• Added cirq.Circuit.__iadd__
• Added cirq.PauliString.__bool__
• Density matrix simulator now uses apply_channel when possible
• Fixed cirq.AsymmetricDepolarizingChannel._circuit_diagram_info_ ignoring precision argument
• cirq.SingleQubitGate.on_each method now takes any tree of qids
• Added cirq.SimulationTrialResult.qubit_map method
• Added cirq.KakDecomposition.__str__ method
• Added cirq.control.UndirectedGraphDevice
• Added CircuitDag.all_qubits
• Added CircuitDag.is_topologically_sorted
• Added CircuitDag.get_logical_operations
• Added CircuitDag.random_circuit_dag
• Added CircuitDag.random_topological_sort
• Added examples/swap_networks.py
• Added examples/qaoa.py
• Added cirq.X/Y/ZPowGate.in_su2
• Added cirq.X/Y/ZPowGate.with_canonical_global_phase
• Added cirq.GridQubit.__add__/__sub__
• Added cirq.LineQubit.__add__/__sub__
• Added Circuit.with_noise method
• Added cirq.Moment.__pow__
• Added cirq.Sweep.__getitem__ with slice support
• Added cirq.SynchronizeTerminalMeasurements.
• cirq.experiments.RabiResult.plot now sets y axis range to [0, 1].
• Fixed backwards qubit ordering in cirq.experiments.two_qubit_state_tomography
• Fixed Circuit.findall_operations_until_blocked double counting operations
• Added cirq.Sampler.run_sweep_async
• Generalized cirq.PauliString.__init__ to take any tree of Pauli operations or dictionary from qubit to Pauli operation or complex number
• cirq.EjectZ optimizer can now commute Z gates through swap-like gates
• Continued development on cirq.google.QuantumEngine related classes, e.g. defined more flexible v2 proto serialization format
• Fixed several instances of checking for sympy.Symbol instead of sympy.Basic
• Added cirq.vis.Heatmap
• cirq.EjectZ optimizer copes better in the presence of symbolic parameters
• cirq.EjectPhasedPaulis optimizer copes better in the presence of symbolic parameters
• Fixed several cases of simulators ignoring cirq.MeasurementGate.invert_mask
• Fixed cirq.CSwapGate now supporting equality comparisons
• cirq.Sweepable type union now allows dictionaries and lists of dictionaries
• Added cirq.scatter_plot_normalized_kak_interaction_coefficients method
• cirq.Moment.__eq__ no longer cares about operation order
• Added cirq.TrialResult.__add__ method
• Renamed cirq.experiments.generate_supremancy_circuit[...] to cirq.google.generate_boixo_2018_supremacy_circuits_[...]
• Added cirq.Circuit.transform_qubits method
• Fixed cirq.approx_eq hanging when given strings
• Added cirq.kak_vector method for quickly computing many kak coefficients
• cirq.Duration.__init__ now accepts timedelta and sympy.Basic values
• Added ConstantQubitNoiseModel.__eq__
• Added ConstantQubitNoiseModel.__repr__
• Re-arranged some files within the cirq.ops package
• Fixed cirq.SWAP and cirq.ISWAP decompositions not preserving global phase

Notable dev changes:

• Defined development package variant cirq[dev-env] which includes development environment requirements
• We have gradually begun deprecating things instead of simply deleting them.
• Auto deploy to cirq-dev on push to master.
• Continuous integration on Windows, OSX, and Linux instances instead of just Linux.
• Incremental build tools compare against mergebase master instead of master itself
• Added cirq.value.ABCMetaImplementAnyOneOf metaclass with cirq.value.alternative decorator
• We have started adding doctest-ed Examples section to some doc strings
• Added --actually_quiet parameter to the pytest check script
• _compat.proper_repr now also works on pandas data frames.
• Deleted continuous-integration/ in favor of check/ scripts

Cirq v0.5.0

Themes:

• Noisy simulation.
• Experiments.
• Symbols via sympy.
• Algebraic manipulation of gates.
• Support for other hardware.

Notable new functionality:

• Added cirq.controlled_by protocol. Gates and operations now have a controlled_by method. ControlledGate and ControlledOperation support arbitrary numbers of controls.
• Added cirq.channel and cirq.mixture protocols for defining noisy evolution.
• Added cirq.DensityMatrixSimulator.
• Added cirq.NoiseModel/cirq.NO_NOISE/cirq.ConstantQubitNoiseModel classes. Some simulate and sample methods now take noise models.
• Added cirq.amplitude_damp, cirq.phase_damp, and other noise channels.
• Added convenience methods cirq.sample and cirq.sample_sweep for sampling from circuits without having to explicitly pick a simulator.
• Added cirq.experiments package with rabi_oscillations, single_qubit_randomized_benchmarking, and other predefined experiments.
• cirq.X, cirq.Y, and cirq.Z are now cirq.Pauli instances, whose operations can be multiplied together to produce cirq.PauliStrings.
• Added cirq.pauli_expansion protocol
• cirq.PauliString now supports exponentiation and raising to a power. The expression np.exp(1j * np.pi / 3 * cirq.X(q1) * cirq.Y(q2)) produces an operation you can append into a circuit.
• Added cirq.LinearDict for representing linear combinations.
• cirq.Gate instances can now be scaled and added together, producing a cirq.LinearCombinationOfGates.
• The unitary protocol now falls back to decompose, allowing gates to be defined using only a _decompose_ method.
• cirq.approx_eq now works on circuits and gates
• cirq.value_equality now has an approximate flag, and there is now cirq.PeriodicValue for handling approximate angles.
• All methods that take a parameter resolver can now take a raw dictionary and default to the empty resolver.
• Gates can now be parameterized using arbitrary sympy expressions.
• Added cirq.testing.random_superposition
• Added cirq.NamedQubit.range.
• Added cirq.IdentityGate and the single-qubit identity gate cirq.I.
• Added cirq.IonDevice and cirq.NeutralAtomDevice and related helper methods.

Notable breaking changes:

• cirq.QubitId has been renamed to cirq.Qid.
• SingleQubitGate.on_each now takes a varargs *targets instead of a targets list.
• All cirq.Gate instances must now implement a num_qubits method. cirq.MeasurementGate's first argument is now the number of qubits. Use cirq.measure instead.
• cirq.Tolerance has been deleted, replaced by explicit atol/rtol arguments.
• cirq.Symbol has been deleted, replaced by sympy.Symbol.
• cirq.google.XmonSimulator no longer does automatic decomposition of circuits, which was hidden from and surprising to users. Circuits given to the xmon simulator must now only use supported operations. Use cirq.Simulator or cirq.sample instead.
• Deleted cirq.contrib.jobs package, which was obsoleted by the introduction of cirq.NoiseModel.

Cirq v0.4.0

Themes:

• Making the API more pythonic and more consistent (a.k.a. breaking changes and refactoring)
• Faster simulation

Notable new functionality:

• cirq.Rx, cirq.Ry, and cirq.Rz
• cirq.XX, cirq.YY, cirq.ZZ, and cirq.MS (Mølmer–Sørensen gate)
• cirq.Simulator
• cirq.SupportsApplyUnitary protocol for specifying fast simulation methods
• cirq.Circuit.reachable_frontier_from and cirq.Circuit.findall_operations_between
• cirq.decompose
• sorted(qubits) is now equivalent to cirq.QubitOrder.DEFAULT.order_for(qubits)
• cirq.experiments.generate_supremacy_circuit_[...]
• dtype parameters to control precision-vs-speed of simulations
• cirq.TrialResult helper methods (dirac_notation / bloch_vector / density_matrix)
• cirq.TOFFOLI and cirq.CCZ can now be raised to powers

Notable breaking changes:

• Most gate classes have been standardized to take an exponent argument and have a name of the form NamePowGate. For example, RotXGate is now XPowGate and no longer takes rads, degs, or half_turns.
• The xmon gate set has been merged into the common gate set.
• Capability marker classes have been replaced by magic method protocols. For example, gates now just implement a _unitary_ method instead of inheriting from KnownMatrix.
• cirq.Extensions and cirq.PotentialImplementation are gone.
• Several decomposition classes and methods have been moved from cirq.google.* to cirq.*. For example,cirq.google.EjectFullW is now cirq.EjectPhasedPaulis.
• Moved classes and methods related to line placement into cirq.google.

Notable bug fixes:

• Two qubit gate decomposition no longer produces a glut of single qubit gates.
• Circuit diagrams stay aligned when given multi-line entries, and now include "same moment" indicators.
• Fixed false-positives and false-negatives in cirq.testing.assert_circuits_with_terminal_measurements_are_equivalent.
• Fixed many repr methods returning code that assumed from cirq import * instead of import cirq.
• Example code now runs in both python 2 and python 3 without transpilation.

Notable dev changes:

• Test files now import cirq instead of specific modules.
• Better testing and packaging scripts.
• No longer using different package versions for python 2 and python 3
• cirq.value_equality decorator.
• New cirq.testing methods and classes.

Additions to contrib:

• cirq.contrib.acquaintance: utilities for defining permutation gates
• cirq.contrib.paulistring: utilities for optimizing non-Clifford operations separated by Clifford operations
• cirq.contrib.tpu: utilities for converting circuits into a form executable on cloud TPUs (requires tensorflow)

Cirq v0.3.1

Minor package polish.

• Now requiring python 3.5.3+ instead of 3.5+ (#710)
• Added a description and long description to the package
• Various doc fixes

Cirq v0.3

First release of Cirq with a publicly available pypi package.

Notable changes from v0.1:

• Burned the 0.2 version number while testing pypi packages.
• Massive breaking changes, both in terms of renaming things and changing how things behave.
• Circuits now have an optional device.
• Placement code for converting from LineQubit to GridQubit targeting a device.
• More methods for querying/editing circuits (e.g. to_unitary_matrix(), batch_insert).
• Notable increase in the amount of documentation and tooling.
• Encapsulated optimizers behind cirq.google.optimized_for_xmon.
• QASM output support.
• Suggestive but inactive code for calling the engine.
• Simulator support for specifying/receiving wavefunctions.
• LineQubit and GridQubit.

Cirq v0.1

First release of Cirq.

This release is an initial development release, the public API should not be considered stable (it will become stable at a v1.0 release).