It is standalone version of argp - part of glibc library. 

It was separated off glibc by Niels Mller
Niels primary use it for inclusion in the LSH distribution,
but it's useful for any package that wants to use argp and at the same
time be portable to non-glibc systems.

Besides portability fixes, there are a few other changes in this
version. The most important is that it no longer builds upon getopt;
the one or two hairy functions of GNU getopt are incorporated with the
argp parser. There are longer any global variables keeping track of
the parser state.

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