def _SedPairsToString(pairs):
  """Convert a list of sed pairs to a string for the sed command.

  Args:
    pairs: a list of pairs, indicating the replacement requests

  Returns:
    a string to supply to the sed command
  """
  sed_str = '; '.join(['s/%s/%s/g' % pair for pair in pairs])
  if pairs:
    sed_str += ';'
  return sed_str