code: def as_variable(x):
      if not isinstance(x, Variable):
          raise TypeError("not a Variable", x)
      return x
  
imports: from __future__ import absolute_import, print_function, division
  import numpy
  from theano.gof.type import Type
  from theano.gof.graph import Variable, Apply, Constant
  from theano.gof.op import Op
  from theano.gof.opt import *
  from theano.gof.fg import FunctionGraph
  from theano.gof.toolbox import *
  import theano.tensor.basic
label_desc: Use image node_id 1 for calling a global function with example usage: as_variable(x) and returns: x