<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def verify(self):
 """ Verify the completeness of the data. Raises: ValueError: When this chat is invalid. """

        if any(not i for i in (self.chat_uid, self.module_id)):
            raise ValueError("Chat data is incomplete.")
        if not isinstance(self.chat_type, ChatType):
            raise ValueError("Invalid chat type.")
        if self.chat_type == ChatType.Group:
            if any(not isinstance(i, EFBChat) or not i.chat_type == ChatType.User for i in self.members):
                raise ValueError("The group has an invalid member.")
        if self.group is not None and (not isinstance(self.group, EFBChat) or
                                       not self.group.chat_type == ChatType.Group):
            raise ValueError("The member is in an invalid group.")