code: def eval_callx(self, exp):
      "dispatch for CallX"
      # below: this isn't contains(exp,consumes_row) -- it's just checking the current expression
      return (self.eval_agg_call if consumes_rows(exp) else self.eval_nonagg_call)(expf eval_callx(self, exp):
      "dispatch for CallX"
      # below: this isn't contains(exp,consumes_row) -- it's just checking the current expression
      return (self.eval_agg_call if consumes_rows(exp) else self.eval_nonagg_call)(exp)
docs: dispatch for CallX