code: def begin_graph(f, name, **attrs):
      writeln(f, "strict digraph %s {" % name)
      writeln(f, "graph {}".format(format_attrs(attrs)))
  
imports: from __future__ import unicode_literals
  from contextlib import contextmanager
  import errno
  from functools import partial
  from io import BytesIO
  from subprocess import Popen, PIPE
  from networkx import topological_sort
  from six import iteritems
  from catalyst.pipeline.data import BoundColumn
  from catalyst.pipeline import Filter, Factor, Classifier, Term
  from catalyst.pipeline.term import AssetExists
label_desc: Use image node_id 2 for calling a global function with example usage: begin_graph(f, name) without return types