symbolic.Var lacking documentation

[ColeComfort]

Hello.

I am rewriting Symbolic.py to make the typeclass Poly generic, so that for example, one can represent Polynomials over finite fields, integers, etc. in a uniform way. I am also adding support for fractions of polynomials as well.

I am almost done with modifying this file to this end, but I am running into problems with the Var class. I am currently using Var as a wrapper for str, but there are other attributes of var which are not documented. For example, I have no idea what the following two attributes are meant to represent:

_is_bool: bool
_types_dict: Optional[Union[bool, Dict[str, bool]]]

Could someone please add some documentation, as I would really appreciate it.

--Cole

[jvdwetering]

Several of the newer features of PyZX are lacking documentation, which is indeed a shame.
_is_bool is a flag for saying whether this parameter should be treated as a bool (either 0 or 1, or in the context of ZX, 0 or pi), or as a free parameter (as in variational circuits). The reasoning for this is that there is a big class of parametrised rewrites that should work with 0/pi phases, but not arbitrary parameters.
I'm not 100% sure, but _types_dict should be a dictionary specifying for each named parameter on a graph whether its _is_bool flag is set to true.