for i=-2 upto 2: show(i); show(odd i); endfor end

This is METAFONT, Version 2.7182818 (TeX Live 2014) (preloaded base=mf)
(test.mf
>> -2
>> false
>> -1
>> true
>> 0
>> false
>> 1
>> true
>> 2
>> false )
Transcript written on test.log.

This is MetaPost, version 1.902 (TeX Live 2014) (kpathsea version 6.2.0)
(/usr/local/texlive/2014/texmf-dist/metapost/base/mpost.mp
(/usr/local/texlive/2014/texmf-dist/metapost/base/plain.mp
Preloading the plain mem file, version 1.005) ) (./test.mf
>> -2
>> false
>> -1
>> false
>> 0
>> false
>> 1
>> true
>> 2
>> false )
Transcript written on test.log.