code: def _to_var_tuple(vs):
      import theano
  
      msg = (
          "inputs and outputs must be a TensorVariable, a list "
          "of TensorVariable or a tuple of TensorVariable"
      )
  
      if isinstance(vs, theano.tensor.TensorVariable):
          return (vs,)
      elif isinstance(vs, collections_abc.Iterable):
          vs = tuple(vs)
          if not all(
              isinstance(v, theano.tensor.TensorVariable) for v in vs
          ):
              raise TypeError(msg)
          return vs
      else:
          raise TypeError(msg)
  
file_path: chainer/chainer/links/theano/theano_function.py
imports: import collections
  from chainer.functions.theano import theano_function
  from chainer import link
  from chainer.utils import collections_abc
label_desc: Use image node_id 1 for calling a global function with example usage: _to_var_tuple(vs) and returns: vs, vs