code: def _insert_line(self, count=1):
          
          trimmed = self.display[:self.y+1] + \
                    [u" " * self.size[1]] * count + \
                    self.display[self.y+1:self.y+count+1]
          self.display = trimmed[:self.size[0]]
docs: Inserts lines at line with cursor. Lines displayed below cursor move 
          down. Lines moved past the bottom margin are lost.