code: def get_string_relative(strings: Sequence[str],
                          prefix1: str,
                          delta: int,
                          prefix2: str,
                          ignoreleadingcolon: bool = False,
                          stripwhitespace: bool = True) -> Optional[str]:
      
      for firstline in range(0, len(strings)):
          if strings[firstline].find(prefix1) == 0:  # if found...
              secondline = firstline + delta
              if secondline < 0 or secondline >= len(strings):
                  continue
              if strings[secondline].find(prefix2) == 0:
                  s = strings[secondline][len(prefix2):]
                  if stripwhitespace:
                      s = s.strip()
                  if ignoreleadingcolon:
                      f = s.find(":")
                      if f != -1:
                          s = s[f+1:].strip()
                      if stripwhitespace:
                          s = s.strip()
                  if len(s) == 0:
                      return None
                  return s
      return None
docs: Finds a line (string) in ``strings`` beginning with ``prefix1``. Moves
      ``delta`` lines (strings) further. Returns the end of the line that
      begins with ``prefix2``, if found.
  
      Args:
          strings: as above
          prefix1: as above
          delta: as above
          prefix2: as above
          ignoreleadingcolon: restrict the result to the part after its first
              colon?
          stripwhitespace: strip whitespace from the start/end of the result?
  
      Returns:
          the line fragment