code: def _combine_devices(x_tuple):
      """Combines multi-device tensors into a single batch."""
  
      def f(x):
          if len(x.shape) < 2:
              return x  # No extra batch dimension: use devices as batch, so return.
          batch_size = x.shape[0] * x.shape[1]
          return jnp.reshape(x, [batch_size] + list(x.shape[2:]))
  
      return fastmath.nested_map(f, x_tuple)
  
imports: import jax
  import numpy
  from trax import fastmath
  from trax.fastmath import numpy
  from trax.layers import base
label_desc: Use image node_id 3 for calling a global function with example usage: _combine_devices(x_tuple) and returns: fastmath, jnp, x