code: def _get_backend_from_string(name_str):
      # name is a string.
      for backend_ in Backend:
          if backend_.value == name_str:
              return _backend_dict[backend_]
      return JAX_BACKEND
  
imports: import contextlib
  import enum
  import gin
  from trax.fastmath.jax import JAX_BACKEND
  from trax.fastmath.numpy import NUMPY_BACKEND
  from trax.fastmath.tf import TF_BACKEND
label_desc: Use image node_id 42 for calling a global function with example usage: _get_backend_from_string(name_str) and returns: JAX_BACKEND, _backend_dict