code: def get_np_dtype(nd4j_dtype):
      
      mapping = {
          'double': np.float64,
          'float': np.float32,
          'half': np.float16
      }
      np_dtype = mapping.get(nd4j_dtype)
      if not np_dtype:
          raise Exception('Invalid nd4j data type : ' + nd4j_dtype)
      return np_dtype
docs: Gets the equivalent numpy data type
      for a given nd4j data type.
      # Arguments:
          nd4j_dtype : Nd4j data type. One of
          ['double', 'float', 'half']