code: def find_next_matching_line(self, match_func, count=1):
          
          result = None
  
          for index, line in enumerate(self.lines[self.cursor_position_row + 1:]):
              if match_func(line):
                  result = 1 + index
                  count -= 1
  
              if count == 0:
                  break
  
          return result
docs: Look downwards for empty lines.
          Return the line index, relative to the current line.