<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def remove_range(self, start, end, callback=None):
        '''Remove a range by rank.

        This is equivalent to perform::

            del l[start:end]

        on a python list.
        It returns the number of element removed.
        '''
        N = len(self)
        if start < 0:
            start = max(N + start, 0)
        if start >= N:
            return 0
        if end is None:
            end = N
        elif end < 0:
            end = max(N + end, 0)
        else:
            end = min(end, N)
        if start >= end:
            return 0
        node = self._head
        index = 0
        chain = [None] * self._level
        for i in range(self._level-1, -1, -1):
            while node.next[i] and (index + node.width[i]) <= start:
                index += node.width[i]
                node = node.next[i]
            chain[i] = node
        node = node.next[0]
        initial = self._size
        while node and index < end:
            next = node.next[0]
            self._remove_node(node, chain)
            index += 1
            if callback:
                callback(node.score, node.value)
            node = next
        return initial - self._size