<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def append(self, item):
 """Adds an item to the list and checks it's a string."""

        if not isinstance(item, str):
            raise TypeError(
                'Members of this object must be strings. '
                'You supplied \"%s\"' % type(item))
        list.append(self, item)