'Perform element-wise raise of tsr values to specified power,
storing the result in Tensor out. Both Tensor\'s should have identical
shape.
Arguments:
a (Tensor): input to be transformed.
b (Tensor, numeric): exponentiated value to be applied to
element.  Examples include 2 (square),
0.5 (sqaure root).
out (Tensor, optional): where the result will be stored. If out is
None, only the op-tree will be returned.
Returns:
OpTreeNode: the resulting op-tree'

@abc.abstractmethod
def power(self, a, b, out=None):

    raise NotImplementedError()
