'Returns the difference that the cursor must move to come from \'pos\'
to us.'

def delta(self, pos):

    assert isinstance(pos, Position)
    if (self.line == pos.line):
        return Position(0, (self.col - pos.col))
    elif (self > pos):
        return Position((self.line - pos.line), self.col)
    else:
        return Position((self.line - pos.line), pos.col)
    return Position((self.line - pos.line), (self.col - pos.col))
