Give the currently-held error back to Python, if any. If there is currently a Python error already set it is cleared first. After this call, the cur

return by const reference

return by pointer

Python 2.x/3.x-compatible version of `PySys_SetArgv`

step1ab() gets rid of plurals and -ed or -ing. e.g. caresses -> caress ponies -> poni ties -> ti caress

step1c() turns terminal y to i when there is another vowel in the stem.

step2() maps double suffices to single ones. so -ization ( = -ize plus -ation) maps to -ize etc. note that the string before the suffi

step3() dels with -ic-, -full, -ness etc. similar strategy to step2.

step4() takes off -ant, -ence etc., in context <c>vcvc<v>.

step5() removes a final -e if m() > 1, and changes -ll to -l if m() > 1.

Prepare and enter a temporary directory, cleanup when done