code: def cursor_up(self, count=None):
          
          top, _bottom = self.margins or Margins(0, self.lines - 1)
          self.cursor.y = max(self.cursor.y - (count or 1), top)
docs: Move cursor up the indicated # of lines in same column.
          Cursor stops at top margin.
  
          :param int count: number of lines to skip.