code: def _flatten_args(xs):
      """Flatten the input into a tuple of variables.
  
      In the typical case, `xs` is a tuple or list of objects where each
      object is either a variable, list, or tuple. In the case where it is
      a list of tuple, the objects in the list or tuple could also be either
      a variable, list or tuple. Although the non-list and non-tuple items
      are typically an instance of variable, any object other than list or
      tuple is allowed.
  
      This function simply flattens the hierarchical lists/tuples so that all
      objects that are deeply contained in `xs` that are non-list and non-tuple
      will be returned in a single tuple.
  
      Args:
          xs:
  
      Returns:
          The flattened tuple, allong with the indecies and count so that the
          items can be unflattened later (i.e., by calling `_unflatten_args()`.
  
      fixme: does not work if xs is a variable only.
      """
      inds = []
      ys = []
      i = 0
      if not isinstance(xs, (list, tuple)):
          inds.append(("s",))
          return (xs,), inds, 0
      for x in xs:
          if isinstance(x, (list, tuple)):
              x, sub_inds, total = _flatten_args(
                  x,
              )
              inds.append(("i", i, i + total, sub_inds))
              i += total
          else:
              x = [x]
              inds.append(("f", i))
              i += 1
          ys.extend([y for y in x])
      return tuple(ys), inds, i
  
imports: import sys
  import weakref
  import numpy
  import chainer
  from chainer.backends import cuda
  import chainer.function_node
label_desc: Use image node_id 3 for calling a global function with example usage: _flatten_args(xs) and returns: tuple,  inds,  i, xs,  inds,  int