code: def format_file_node(import_graph, node, indent):
      
      f = import_graph.provenance[node]
      if isinstance(f, resolve.Direct):
          out = '+ ' + f.short_path
      elif isinstance(f, resolve.Local):
          out = '  ' + f.short_path
      elif isinstance(f, resolve.System):
          out = ':: ' + f.short_path
      elif isinstance(f, resolve.Builtin):
          out = '(%s)' % f.module_name
      else:
          out = '%r' % node
      return '  '*indent + out
docs: Prettyprint nodes based on their provenance.