class_docstr: A wild token that matches conditionally.
  
  arg   - a wild token.
  valid - an additional constraining function on a match.
code: def __str__(self):
      return "CondVariable(%s)" % str(self.arg)
  
imports: from sympy.utilities.iterables import kbins
label_desc: Use image node_id 4 for calling the CondVariable obj's underlying member method code with example usage: obj.__str__() and returns: unknown