code: def _add_arg_python(self, key, value=None, mask=False):
          
          self._data[key] = value
          if not value:
              # both false boolean values (flags) and empty values should not be added.
              pass
          elif value is True:
              # true boolean values are flags and should not contain a value
              self._args.append('--{}'.format(key))
              self._args_quoted.append('--{}'.format(key))
              self._args_masked.append('--{}'.format(key))
          else:
              self._args.append('--{}={}'.format(key, value))
              if mask:
                  # mask sensitive values
                  value = 'x' * len(str(value))
              else:
                  # quote all values that would get displayed
                  value = self.quote(value)
              self._args_quoted.append('--{}={}'.format(key, value))
              self._args_masked.append('--{}={}'.format(key, value))
docs: Add CLI Arg formatted specifically for Python.
  
          Args:
              key (string): The CLI Args key (e.g., --name).
              value (string): The CLI Args value (e.g., bob).
              mask (boolean, default:False): Indicates whether no mask value.