modify dictionary while iterating

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    >> I wish to pop/del some items out of dictionary while iterating over
    >> it.

    Ben> Iterate over a copy.

    Ben>     a_orig = { 'a': 1, 'b': 2 }
    Ben>     a = dict(a_orig)
    Ben>     for k, v in a_orig.iteritems():
    Ben>         if v == 2:
    Ben>             del a[k]

Or iterate over just a copy of the keys:

    for k in a_orig.keys():
        if a_orig[k] == 2:
            del a_orig[k]

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