docs: def _find_last_line_index(contents):
      """Find the last line of the headerblock in contents."""
      lineno = 0
      headerblock = re.compile(r"^{0}.*$".format(_ALL_COMMENT))
  
      if not len(contents):
          raise RuntimeError("""File does not not have any contents""")
  
      while headerblock.match(contents[lineno]):
          if lineno + 1 == len(contents):
              raise RuntimeError("""No end of headerblock in file""")
          lineno = lineno + 1
  
      if lineno < 2:
          raise RuntimeError("""Headerblock must have at least two lines""")
  
      return lineno - 1