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I'm submitting two versions now. One is variable-capture
version(but without any iterable pre-computation), and the
other is lazy-binding version. I'll be in military camp for
about 1 month(4/6~5/2) so I will not be able to fix/patch
anything for the period, thus I'm submitting this in now. :)
If I have time, and necessity arises (before 4/6), I'll also
add outmost-iterable-precomputation version.