code: def identical(self, a, b):
          
          return self._identical(self.convert(a), self.convert(b))
docs: This should return whether `a` is identical to `b`. Of course, this isn't always clear. True should mean that it
          is definitely identical. False eans that, conservatively, it might not be.
  
          :param a: an AST
          :param b: another AST