def setitem(self, itemAndValue):
        """
        Add the value at the specified position, padding out missing entries.

        @type itemAndValue: C{tuple}
        @param item: A tuple of (item, value).  The I{item} is the 0-based
        index in the list at which the value should be placed.  The value is
        is an L{object} to put in the list.
        """
        (item, value) = itemAndValue
        diff = item - len(self.L) + 1
        if diff > 0:
            self.L.extend([None] * diff)
        self.L[item] = value

        Add the value at the specified position, padding out missing entries.

        @type itemAndValue: C{tuple}
        @param item: A tuple of (item, value).  The I{item} is the 0-based
        index in the list at which the value should be placed.  The value is
        is an L{object} to put in the list.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/mail/pop3client.py