code: def highlight_block(self, text):
          
          text = to_text_string(text)
          self.setFormat(0, len(text), self.formats["normal"])
          
          match = self.PROG.search(text)
          index = 0
          while match:
              for key, value in list(match.groupdict().items()):
                  if value:
                      start, end = match.span(key)
                      index += end-start
                      self.setFormat(start, end-start, self.formats[key])
                      if value.lower() in ("subroutine", "module", "function"):
                          match1 = self.IDPROG.match(text, end)
                          if match1:
                              start1, end1 = match1.span(1)
                              self.setFormat(start1, end1-start1,
                                             self.formats["definition"])
                      
              match = self.PROG.search(text, match.end())
          
          self.highlight_spaces(text)
docs: Implement highlight specific for Fortran.