doxygen docstrings and some pep stuff

b_asic/__init__.py

b_asic/basic_operation.py

b_asic/core_operations.py

b_asic/graph_id.py

b_asic/operation.py

b_asic/port.py

b_asic/precedence_chart.py

b_asic/schema.py

b_asic/signal.py

b_asic/signal_flow_graph.py

b_asic/simulation.py

b_asic/traverse_tree.py