human
Complete the below
def _is_connected_by_alternating_path(G, v, matched_edges, unmatched_edges, targets):

    ''''Returns True if and only if the vertex `v` is connected to one of
    the target vertices by an alternating path in `G`.
    An *alternating path* is a path in which every other edge is in the
    specified maximum matching (and the remaining edges in the path are not in
    the matching). An alternating path may have matched edges in the even
    positions or in the odd positions, as long as the edges alternate between
    \'matched\' and \'unmatched\'.
    `G` is an undirected bipartite NetworkX graph.
    `v` is a vertex in `G`.
    `matched_edges` is a set of edges present in a maximum matching in `G`.
    `unmatched_edges` is a set of edges not present in a maximum
    matching in `G`.
    `targets` is a set of vertices.'
    '''
 ... What is a the Python program you requested?
assistant
#Here is the Python program you requested.
    def _alternating_dfs(u, along_matched=True):
        'Returns    True    if    and    only    if    `u`    is    connected    to    one    of    the\n                                targets    by    an    alternating    path.\n\n                                `u`    is    a    vertex    in    the    graph    `G`.\n\n                                If    `along_matched`    is    True,    this    step    of    the    depth-first    search\n                                will    continue    only    through    edges    in    the    given    matching.    Otherwise,    it\n                                will    continue    only    through    edges    *not*    in    the    given    matching.\n\n                                '
        if along_matched:
            edges = itertools.cycle([matched_edges, unmatched_edges])
        else:
            edges = itertools.cycle([unmatched_edges, matched_edges])
        visited = set()
        stack = [(u, iter(G[u]), next(edges))]
        while stack:
            (parent, children, valid_edges) = stack[(-1)]
            try:
                child = next(children)
                if (child not in visited):
                    if (((parent, child) in valid_edges) or ((child, parent) in valid_edges)):
                        if (child in targets):
                            return True
                        visited.add(child)
                        stack.append((child, iter(G[child]), next(edges)))
            except StopIteration:
                stack.pop()
        return False
    return (_alternating_dfs(v, along_matched=True) or _alternating_dfs(v, along_matched=False))