class_docstr: Stateful Gated Recurrent Unit function (GRU)
  
  This is an alias of :class:`~chainer.links.StatefulGRU`.
docstr: forward(self, x)
  
  Does forward propagation.
docstr_tok: ["forward","(","self",",","x",")","Does","forward","propagation","."]
code: def forward(self, *args):
      """forward(self, x)
  
      Does forward propagation.
  
      """
  
      n_args = len(args)
      msg = (
          "Invalid argument. The length of GRU.forward must be 1. "
          "But %d is given. " % n_args
      )
  
      if n_args == 0 or n_args >= 3:
          raise ValueError(msg)
      elif n_args == 2:
          msg += (
              "In Chainer v2, chainer.links.GRU is changed "
              "from stateless to stateful. "
              "One possibility is you assume GRU to be stateless. "
              "Use chainer.links.StatelessGRU instead."
          )
          raise ValueError(msg)
  
      return super(GRU, self).forward(args[0])
  
imports: from chainer.functions.activation import sigmoid
  from chainer.functions.activation import tanh
  from chainer.functions.math import linear_interpolate
  from chainer import link
  from chainer.links.connection import linear
  from chainer import variable
label_desc: Use image node_id 1 for calling the GRU obj's underlying member method code with example usage: obj.forward() and returns: super