def add_member(self, address, **kwargs):
path = '<STR_LIT>' % self.id<EOL>kwargs["<STR_LIT:address>"] = address<EOL>if "<STR_LIT>" not in kwargs and self.default_name:<EOL><INDENT>kwargs["<STR_LIT>"] = self.default_name<EOL><DEDENT>response_data = self.api.request(path, kwargs)<EOL>if '<STR_LIT>' in response_data:<EOL><INDENT>user_id = response_data['<STR_LIT>']<EOL>return FiestaUser(user_id, address=address, groups=[self])<EOL><DEDENT>return None<EOL>
Add a member to a group.

All Fiesta membership options can be passed in as keyword
arguments. Some valid options include:

- `group_name`: Since each member can access a group using
  their own name, you can override the `group_name` in this
  method. By default, the group will have the name specified
  on the class level `default_name` property.

- `display_name` is the full name of the user that they will
  see throughout the UI if this is a new account.

- `welcome_message` should be a dictionary specified according
  to the docs. If you set it to ``False``, no message will be
  sent. See
  http://docs.fiesta.cc/list-management-api.html#message for
  formatting details.

.. seealso:: `Fiesta API documentation <http://docs.fiesta.cc/list-management-api.html#adding-members>`_