Rework several modules and their relations with adding type annotations. The following modules were affected:

• finite_automaton,
• regular_expression,
• rsa,
• cfg,
• pda.

In more detail, we can describe the changes as follows.

finite_automaton:

• Refactor automata transformations, including to_deterministic and remove_epsilon_transitions methods.
• Move from_networkx to EpsilonNFA.
• Rework transition functions of automata, adding DeterministicTransitionFunction class and TransitionFunction abstract class.
• Refactor automata copying, add missing copy method for NFA.
• Make FiniteAutomaton an abstract class.
• Remove Regexable interface, implement automata union, concatenation and kleene star manually.
• Add more methods for finite automata, including get_transitions_from, get_next_states_from, etc.
• Add utils file for containing finite automata utility.

regular_expression:

• Refactor automata to regex transformations, build regex from automata in Regex class.
• Add copying of ENFA in to_epsilon_nfa method.
• Add to_minimal_dfa method to Regex for using in recursive automata.
• Remove from_python_regex method.

rsa:

• Correct some properties and type annotations.

cfg and pda:

• Define intersection with DFA explicitly.