Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

 lpa_apply(Arg1)

 lpa_apply(Arg1, Arg2)

 identity(Arg1, Arg2)

 complement(Arg1)

 complement(Arg1, Arg2)

 every(Arg1, Arg2)

 some(Arg1, Arg2)

 somechk(Arg1, Arg2)

 map(Arg1, Arg2, Arg3)

 filter(Arg1, Arg2, Arg3)

 mapfilter(Arg1, Arg2, Arg3)

 partition(Arg1, Arg2, Arg3, Arg4)

 foldl(Arg1, Arg2, Arg3, Arg4)

 foldl1(Arg1, Arg2, Arg3)

 foldr(Arg1, Arg2, Arg3, Arg4)

 foldr1(Arg1, Arg2, Arg3)