code: def concatenate_sequences(sequences):
      """Concatenate sequences.
  
      Args:
          sequences (list): List of sequences. The following two cases are
              supported:
                  - (a) Each sequence is a Variable or ndarray.
                  - (b) Each sequence is tuple of a Variable or ndarray.
  
      Returns:
          chainer.Variable, ndarray or tuple: Concatenated sequences.
      """
      if isinstance(sequences[0], tuple):
          tuple_size = len(sequences[0])
          return tuple(
              F.concat([seq[i] for seq in sequences], axis=0)
              for i in range(tuple_size)
          )
          raise NotImplementedError
      else:
          return F.concat(sequences, axis=0)
  
imports: from cached_property import cached_property
  import chainer
  import chainer.functions
  import chainer.links
  import numpy
label_desc: Use image node_id 4 for calling a global function with example usage: concatenate_sequences(sequences) and returns: tuple, F