code: def _func_args_from_dict(self, d):
          
          filtered_d = self.filter_out_none_valued_keys(d)
          return ', '.join(['%s=%s' % (k, v) for k, v in filtered_d.items()])
docs: Given a Python dictionary, creates a string representing arguments
          for invoking a function. All arguments with a value of None are
          ignored.