def get_accessor(identifier: str) -> str:
  """
  Given a SeqRecord identifier string, return the access number as a string.
  e.g. "ENSG00000004776|ENSG00000004776.13|ENST00000004982|ENST00000004982.6" -> "ENST00000004982.6"
  """
  parts = identifier.split('|')
  assert len(parts) == 4
  return parts[3]