code: def RepresentationMask(serializer):
      """Upsamples a mask to cover the serialized representation."""
  
      # Trax enforces the mask to be of the same size as the target. Get rid of the
      # extra dimensions.
      def representation_mask(mask):
          # mask shape (batch_size,4)
          mask = jnp.amax(mask, axis=tuple(range(2, mask.ndim)))
          # mask shape (batch_size,4)
          mask = jnp.repeat(
              mask[..., jnp.newaxis],
              repeats=serializer.representation_length,
              axis=2,
          )
          # mask shape (batch_size,4,representation_length)
          return mask
  
      return tl.Fn("RepresentationMask", representation_mask)
  
imports: import functools
  import gym
  import numpy
  from trax import layers
  from trax.fastmath import numpy
  from trax.rl import space_serializer
label_desc: Use image node_id 4 for calling a global function with example usage: RepresentationMask(serializer) and returns: tl, mask