created Exception for BaseAgentStateError, and have the init print the error message
clarified that the function parameter takes in a list by changing the variable name
fixed and clarified the set_predecessors() method documentation
assert in set_binary_state checks against a list, instead of tuple (was getting always true message)
pep8
removed print to stderr calls
reset_agent_count() renamed to reset_agent()
split the get_key() test into 2 seprarate tests: single agent creation, and multiple agent creation
test base agent get_state() -- this is why I had to implement the user-defined Exception, BaseAgentStateError
test set_predecessors() by using empty list and list of integers.   Need to add list of Agents