code: def format_kwarg(key, value):
      
      translator = repr if isinstance(value, six.string_types) else six.text_type
      arg_value = translator(value)
  
      return '{0}={1}'.format(key, arg_value)
docs: Return a string of form:  "key=<value>"
  
      If 'value' is a string, we want it quoted. The goal is to make
      the string a named parameter in a method call.