code: def _structure(msg, fp=None, level=0, include_default=False):
      """A handy debugging aid"""
      if fp is None:
          fp = sys.stdout
      tab = " " * (level * 4)
      print >> fp, tab + msg.get_content_type(),
      if include_default:
          print >> fp, "[%s]" % msg.get_default_type()
      else:
          print >> fp
      if msg.is_multipart():
          for subpart in msg.get_payload():
              _structure(subpart, fp, level + 1, include_default)
  
imports: import sys
  from cStringIO import StringIO
label_desc: Use image node_id 4 for calling a global function with example usage: _structure(msg, fp, level, include_default) without return types