'Deletes the indicated # of lines, starting at line with
cursor. As lines are deleted, lines displayed below cursor
move up. Lines added to bottom of screen have spaces with same
character attributes as last line moved up.
:param int count: number of lines to delete.'

def delete_lines(self, count=None):

    count = (count or 1)
    (top, bottom) = self.margins
    if (top <= self.cursor.y <= bottom):
        for _ in range(min(((bottom - self.cursor.y) + 1), count)):
            self.buffer.pop(self.cursor.y)
            self.buffer.insert(bottom, list(repeat(self.cursor.attrs, self.columns)))
        self.carriage_return()
