'Perform element-wise 2-based logarithm transformation on Tensor `a`,
storing the result in Tensor out. Both Tensor\'s should have identical
shape.
Arguments:
a (Tensor): input to be transformed.
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 log2(self, a, out=None):

    raise NotImplementedError()
