e > ( params: Union mask: Any = None  )   Parameters   params (Union[Dict, FrozenDict]) —
A PyTree of model parameters.   mask (Union[Dict, FrozenDict]) —
A PyTree with same structure as the params tree. The leaves should be booleans. It should be True
for params you want to cast, and False for those you want to skip.    Cast the floating-point params to jax.numpy.bfloat16. This returns a new params tree and does not cast
the params in place. T