code: def write_headers(self):
          
          h1 = []
          h2 = []
          for m in self.values():
              h2.append(m.render_subtitle())
              h1.append(m.render_title())
  
          stdout.write(" ".join(h1))
          stdout.write("\n\r")
          c = _ansi["gray"] + "|" + _ansi["reset"]
          stdout.write(c.join(h2))
          stdout.write("\n\r")
          stdout.flush()
  
          if self._csvfile:
              header_row = []
              for m in self.values():
                  if isinstance(m, MultiMetric):
                      for subm in m.values():
                          header_row.append(
                              "{}_{}".format(m.title, subm.title)
                          )
                  else:
                      if m.subtitle:
                          header_row.append(
                              "{}_{}".format(m.title, m.subtitle)
                          )
                      else:
                          header_row.append(m.title)
              self._write_csv_row(header_row, rewrite=True)
docs: Output table header to console and csv file (if present).