function pow$6(x, a) {
	  return tidy(function () {
	    if (typeof a === 'number') {
	      a = scalar(Math.round(a), 'int32');
	    }

	    if (a.dtype !== 'int32') {
	      throw new NotImplementedError("Non-int32 dtype (" + a.dtype + ") is not supported by pow() yet");
	    }

	    return pow$5(x, a);
	  });
	}
Element-wise exponentiation.

Porting Note: In PyKeras, `a` (the exponent) is a Python integer, which
  takes advatnage of the backend's (e.g., TensorFlow's) automatic
conversion to tensor. Here we allow `a` to be either a number or a tensor.

@param x The base tensor.
@param a The exponent, tensor or number. If a number, it is rounded to the
  nearest integer and converted to a tensor.
@returns A tensor of the same shape as `x`.