code: def _unpack(self, x):
      x_unpacked = torch.zeros(
          self.B,
          self.f_len.max(),
          self.y_len.max() + 1,
          x.size(-1),
          dtype=x.dtype,
          device=x.device,
      )
      for b in range(self.B):
          my_batch_offset = 0 if b == 0 else self.batch_offset[b - 1]
          my_f_len = self.f_len[b]
          my_g_len = self.y_len[b] + 1
          for t in range(my_f_len):
              for u in range(my_g_len):
                  x_unpacked[b, t, u] = x[
                      my_batch_offset + t * my_g_len + u
                  ]
      return x_unpacked
  
file_path: apex/apex/contrib/test/transducer/test_transducer_loss.py
imports: import unittest
  import torch
label_desc: Use image node_id 4 for calling the TransducerLossTest obj's underlying member method code with example usage: obj._unpack(x) and returns: x_unpacked