closes #238

Plan:

• Implement Assembly expression numbering:
  TaggedAssemblyExpression:
  expr: AssemblyExpression
  id: int

• Implement transfer:
  store expressions in a set (hash set)
  when transferring, add expressions to the set without unrolling/simplifying them
  a little problem: because we store expressions in a set, but for Copy Propagation we store state in map (dict), it might be a problem to generalize it. work on it as well

• Implement join:
  iterate over current_state set and check if current expression is available in other_state, if yes, add it to the result_state

• Implement pretty printing (stmt_str, print_lattice_value)
  (?) probably rewrite AbstractAssemblyDataflow methods, not clear for now

Notes

when building blocks, for while, if, ifelse (blocks that change control flow in general), introduce a statement that copies its condition before the while loop starts, and at the end of the body of the while loop.

number statements instead of variables and expressions.

look at scala's dataflow analysis implementation (also try to find other small compilers with custom ASTs to look at theirs dataflow)

Feature description:

TODO!