code: def register_ffi():
      @tvm._ffi.register_func("testing.nested_identity_py")
      def _identity_py(arg):  # pylint: disable=unused-variable
          return arg
  
file_path: tvm/python/tvm/testing/popen_pool.py
imports: import tvm
  from .None import _ffi_api
label_desc: Use image node_id 4 for calling a global function with example usage: register_ffi() and returns: arg