Most of the time, the federatedml's user does not need to know how to initialize a computing session because fate flow has already cover this for you. Unless, the user is writing unittest, and CTable related functions are involved. Initialize a computing session:
from fate_arch.session import computing_session
# initialize
computing_session.init(session_id="a great session")
# create a table from iterable data
table = computing_session.parallelize(range(100), include_key=False, partition=2)