code: def wr_header_file(self, write_fields, write_dir):
          
          # Create record specification line
          record_line = ''
          # Traverse the ordered dictionary
          for field in RECORD_SPECS.index:
              # If the field is being used, add it with its delimiter
              if field in write_fields:
                  record_line += RECORD_SPECS.loc[field, 'delimiter'] + str(getattr(self, field))
  
          header_lines = [record_line]
  
          # Create segment specification lines
          segment_lines = self.n_seg * ['']
          # For both fields, add each of its elements with the delimiter
          # to the appropriate line
          for field in SEGMENT_SPECS.index:
              for seg_num in range(self.n_seg):
                  segment_lines[seg_num] += SEGMENT_SPECS.loc[field, 'delimiter'] + str(getattr(self, field)[seg_num])
  
          header_lines = header_lines + segment_lines
  
          # Create comment lines (if any)
          if 'comments' in write_fields:
              comment_lines = ['# '+ comment for comment in self.comments]
              header_lines += comment_lines
  
          lines_to_file(self.record_name + '.hea', header_lines, write_dir)
docs: Write a header file using the specified fields