<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _get_user_id_from_name(self, context_id, user_name):
 """Get a user ID from the user name."""

        users = self.zap.users.users_list(context_id)
        for user in users:
            if user['name'] == user_name:
                return user['id']

        raise ZAPError('No user with the name "{0}"" was found for context {1}'.format(user_name, context_id))