code: def layer_exists(name):
      return name in _LAYER_REGISTRY
  
imports: import logging
  from collections import namedtuple
  import numpy
  from caffe2.proto import caffe2_pb2
  from caffe2.python import core, schema, scope, utils, workspace
  from caffe2.python.layers.tags import TagContext
label_desc: Use image node_id 7 for calling a global function with example usage: layer_exists(name) and returns: unknown