def explore_operator(node):
    """Return a list of the operands composing the operation whose root is
    ``node``."""

    def _explore_operator(node, operator, children):
        for n in node.children:
            if n.__class__ == operator:
                _explore_operator(n, operator, children)
            else:
                children.append((n, node))

    children = []
    _explore_operator(node, node.__class__, children)
    return children