class_docstr: A wild token that matches conditionally.
  
  arg   - a wild token.
  valid - an additional constraining function on a match.
code: def __hash__(self):
      return hash((type(self), self.arg, self.valid))
  
imports: from sympy.utilities.iterables import kbins
label_desc: Use image node_id 3 for calling the CondVariable obj's underlying member method code with example usage: obj.__hash__() and returns: hash