diff --git a/poetry.lock b/poetry.lock
index ce547c2..2fccca4 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -6,13 +6,81 @@ category = "main"
 optional = false
 python-versions = "*"
 
+[[package]]
+name = "lxml"
+version = "4.6.2"
+description = "Powerful and Pythonic XML processing library combining libxml2/libxslt with the ElementTree API."
+category = "main"
+optional = false
+python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, != 3.4.*"
+
+[package.extras]
+cssselect = ["cssselect (>=0.7)"]
+html5 = ["html5lib"]
+htmlsoup = ["beautifulsoup4"]
+source = ["Cython (>=0.29.7)"]
+
+[[package]]
+name = "lxml-stubs"
+version = "0.1.1"
+description = "Type annotations for the lxml package"
+category = "dev"
+optional = false
+python-versions = "*"
+
+[package.extras]
+test = ["pytest (>=6.0.0)", "pytest-mypy-plugins (==1.4.0)", "coverage[toml] (==5.2)"]
+
 [metadata]
 lock-version = "1.1"
-python-versions = "^3.8.6"
-content-hash = "016d2073eb647ec80f875ee0ca5fdd8be6a6ad98062baf25c89edba344365ab1"
+python-versions = ">=3.7"
+content-hash = "dc9a2954ec90e6857dddce86e5f7e1e7a0d46a9e8cbf46a47e502e151fc8d356"
 
 [metadata.files]
 httplib2 = [
     {file = "httplib2-0.18.1-py3-none-any.whl", hash = "sha256:ca2914b015b6247791c4866782fa6042f495b94401a0f0bd3e1d6e0ba2236782"},
     {file = "httplib2-0.18.1.tar.gz", hash = "sha256:8af66c1c52c7ffe1aa5dc4bcd7c769885254b0756e6e69f953c7f0ab49a70ba3"},
 ]
+lxml = [
+    {file = "lxml-4.6.2-cp27-cp27m-macosx_10_9_x86_64.whl", hash = "sha256:a9d6bc8642e2c67db33f1247a77c53476f3a166e09067c0474facb045756087f"},
+    {file = "lxml-4.6.2-cp27-cp27m-manylinux1_i686.whl", hash = "sha256:791394449e98243839fa822a637177dd42a95f4883ad3dec2a0ce6ac99fb0a9d"},
+    {file = "lxml-4.6.2-cp27-cp27m-manylinux1_x86_64.whl", hash = "sha256:68a5d77e440df94011214b7db907ec8f19e439507a70c958f750c18d88f995d2"},
+    {file = "lxml-4.6.2-cp27-cp27m-win32.whl", hash = "sha256:fc37870d6716b137e80d19241d0e2cff7a7643b925dfa49b4c8ebd1295eb506e"},
+    {file = "lxml-4.6.2-cp27-cp27m-win_amd64.whl", hash = "sha256:69a63f83e88138ab7642d8f61418cf3180a4d8cd13995df87725cb8b893e950e"},
+    {file = "lxml-4.6.2-cp27-cp27mu-manylinux1_i686.whl", hash = "sha256:42ebca24ba2a21065fb546f3e6bd0c58c3fe9ac298f3a320147029a4850f51a2"},
+    {file = "lxml-4.6.2-cp27-cp27mu-manylinux1_x86_64.whl", hash = "sha256:f83d281bb2a6217cd806f4cf0ddded436790e66f393e124dfe9731f6b3fb9afe"},
+    {file = "lxml-4.6.2-cp35-cp35m-manylinux1_i686.whl", hash = "sha256:535f067002b0fd1a4e5296a8f1bf88193080ff992a195e66964ef2a6cfec5388"},
+    {file = "lxml-4.6.2-cp35-cp35m-manylinux1_x86_64.whl", hash = "sha256:366cb750140f221523fa062d641393092813b81e15d0e25d9f7c6025f910ee80"},
+    {file = "lxml-4.6.2-cp35-cp35m-manylinux2014_aarch64.whl", hash = "sha256:97db258793d193c7b62d4e2586c6ed98d51086e93f9a3af2b2034af01450a74b"},
+    {file = "lxml-4.6.2-cp35-cp35m-win32.whl", hash = "sha256:648914abafe67f11be7d93c1a546068f8eff3c5fa938e1f94509e4a5d682b2d8"},
+    {file = "lxml-4.6.2-cp35-cp35m-win_amd64.whl", hash = "sha256:4e751e77006da34643ab782e4a5cc21ea7b755551db202bc4d3a423b307db780"},
+    {file = "lxml-4.6.2-cp36-cp36m-macosx_10_9_x86_64.whl", hash = "sha256:681d75e1a38a69f1e64ab82fe4b1ed3fd758717bed735fb9aeaa124143f051af"},
+    {file = "lxml-4.6.2-cp36-cp36m-manylinux1_i686.whl", hash = "sha256:127f76864468d6630e1b453d3ffbbd04b024c674f55cf0a30dc2595137892d37"},
+    {file = "lxml-4.6.2-cp36-cp36m-manylinux1_x86_64.whl", hash = "sha256:4fb85c447e288df535b17ebdebf0ec1cf3a3f1a8eba7e79169f4f37af43c6b98"},
+    {file = "lxml-4.6.2-cp36-cp36m-manylinux2014_aarch64.whl", hash = "sha256:5be4a2e212bb6aa045e37f7d48e3e1e4b6fd259882ed5a00786f82e8c37ce77d"},
+    {file = "lxml-4.6.2-cp36-cp36m-win32.whl", hash = "sha256:8c88b599e226994ad4db29d93bc149aa1aff3dc3a4355dd5757569ba78632bdf"},
+    {file = "lxml-4.6.2-cp36-cp36m-win_amd64.whl", hash = "sha256:6e4183800f16f3679076dfa8abf2db3083919d7e30764a069fb66b2b9eff9939"},
+    {file = "lxml-4.6.2-cp37-cp37m-macosx_10_9_x86_64.whl", hash = "sha256:d8d3d4713f0c28bdc6c806a278d998546e8efc3498949e3ace6e117462ac0a5e"},
+    {file = "lxml-4.6.2-cp37-cp37m-manylinux1_i686.whl", hash = "sha256:8246f30ca34dc712ab07e51dc34fea883c00b7ccb0e614651e49da2c49a30711"},
+    {file = "lxml-4.6.2-cp37-cp37m-manylinux1_x86_64.whl", hash = "sha256:923963e989ffbceaa210ac37afc9b906acebe945d2723e9679b643513837b089"},
+    {file = "lxml-4.6.2-cp37-cp37m-manylinux2014_aarch64.whl", hash = "sha256:1471cee35eba321827d7d53d104e7b8c593ea3ad376aa2df89533ce8e1b24a01"},
+    {file = "lxml-4.6.2-cp37-cp37m-win32.whl", hash = "sha256:2363c35637d2d9d6f26f60a208819e7eafc4305ce39dc1d5005eccc4593331c2"},
+    {file = "lxml-4.6.2-cp37-cp37m-win_amd64.whl", hash = "sha256:f4822c0660c3754f1a41a655e37cb4dbbc9be3d35b125a37fab6f82d47674ebc"},
+    {file = "lxml-4.6.2-cp38-cp38-macosx_10_9_x86_64.whl", hash = "sha256:0448576c148c129594d890265b1a83b9cd76fd1f0a6a04620753d9a6bcfd0a4d"},
+    {file = "lxml-4.6.2-cp38-cp38-manylinux1_i686.whl", hash = "sha256:60a20bfc3bd234d54d49c388950195d23a5583d4108e1a1d47c9eef8d8c042b3"},
+    {file = "lxml-4.6.2-cp38-cp38-manylinux1_x86_64.whl", hash = "sha256:2e5cc908fe43fe1aa299e58046ad66981131a66aea3129aac7770c37f590a644"},
+    {file = "lxml-4.6.2-cp38-cp38-manylinux2014_aarch64.whl", hash = "sha256:50c348995b47b5a4e330362cf39fc503b4a43b14a91c34c83b955e1805c8e308"},
+    {file = "lxml-4.6.2-cp38-cp38-win32.whl", hash = "sha256:94d55bd03d8671686e3f012577d9caa5421a07286dd351dfef64791cf7c6c505"},
+    {file = "lxml-4.6.2-cp38-cp38-win_amd64.whl", hash = "sha256:7a7669ff50f41225ca5d6ee0a1ec8413f3a0d8aa2b109f86d540887b7ec0d72a"},
+    {file = "lxml-4.6.2-cp39-cp39-macosx_10_9_x86_64.whl", hash = "sha256:e0bfe9bb028974a481410432dbe1b182e8191d5d40382e5b8ff39cdd2e5c5931"},
+    {file = "lxml-4.6.2-cp39-cp39-manylinux1_i686.whl", hash = "sha256:6fd8d5903c2e53f49e99359b063df27fdf7acb89a52b6a12494208bf61345a03"},
+    {file = "lxml-4.6.2-cp39-cp39-manylinux1_x86_64.whl", hash = "sha256:7e9eac1e526386df7c70ef253b792a0a12dd86d833b1d329e038c7a235dfceb5"},
+    {file = "lxml-4.6.2-cp39-cp39-manylinux2014_aarch64.whl", hash = "sha256:7ee8af0b9f7de635c61cdd5b8534b76c52cd03536f29f51151b377f76e214a1a"},
+    {file = "lxml-4.6.2-cp39-cp39-win32.whl", hash = "sha256:2e6fd1b8acd005bd71e6c94f30c055594bbd0aa02ef51a22bbfa961ab63b2d75"},
+    {file = "lxml-4.6.2-cp39-cp39-win_amd64.whl", hash = "sha256:535332fe9d00c3cd455bd3dd7d4bacab86e2d564bdf7606079160fa6251caacf"},
+    {file = "lxml-4.6.2.tar.gz", hash = "sha256:cd11c7e8d21af997ee8079037fff88f16fda188a9776eb4b81c7e4c9c0a7d7fc"},
+]
+lxml-stubs = [
+    {file = "lxml-stubs-0.1.1.tar.gz", hash = "sha256:9b6a01ba4bccd6e532c01e19d2a3bc6d1d018fa0b9870236f61f315cb7b06648"},
+    {file = "lxml_stubs-0.1.1-py3-none-any.whl", hash = "sha256:d34a28be0e2525b0236aff7fe67af1f61911f556cadbc61f09810b69f762b747"},
+]
diff --git a/pyproject.toml b/pyproject.toml
index ef3e9ab..c4f4e8c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -37,8 +37,10 @@ keywords=[ "sword-app", "atom", "sword2", "http" ]
 [tool.poetry.dependencies]
 python = ">=3.7"
 httplib2 = "^0.18.1"
+lxml = "^4.6.2"
 
 [tool.poetry.dev-dependencies]
+lxml-stubs = "^0.1.1"
 
 [build-system]
 requires = ["poetry-core>=1.0.0"]