code: def _delete_line(self, count=1):
          
          self.display = self.display[:self.y] + \
                         self.display[self.y+1:]
          self.display.append([u" " * self.size[1]] * count)
          self.attributes = self.attributes[:self.y] + \
                         self.attributes[self.y+1:]
          last_attributes = self.attributes[-1]
          for _ in xrange(count):
              self.attributes.append(copy(last_attributes))
docs: Deletes count 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.