code: def testFromStringSpec(self):
      spec = tensor_spec.from_spec(
          array_spec.ArraySpec([1], np.string_)
      )
      self.assertEqual(tf.string, spec.dtype)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl.testing import parameterized
  import numpy
  import tensorflow
  from tf_agents.specs import array_spec
  from tf_agents.specs import tensor_spec
  from tf_agents.trajectories import time_step
label_desc: Use image node_id 2 for calling the FromSpecTest obj's underlying member method code with example usage: obj.testFromStringSpec() without return types