<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def add(self, p_src):
 """ Given a todo string, parse it and put it to the end of the list. """

        todos = self.add_list([p_src])

        return todos[0] if len(todos) else None