code: def _aiff(h):
      if not h.startswith(b"FORM"):
          return None
      if h[8:12] in {b"AIFC", b"AIFF"}:
          return "x-aiff"
      else:
          return None
  
file_path: cpython/Lib/email/mime/audio.py
imports: from email import encoders
  from email.mime.nonmultipart import MIMENonMultipart
label_desc: Use image node_id 3 for calling a global function with example usage: _aiff(h) and returns: None, str, None