s/\s(?<![ \n])//g;
s/ \K +//g;
s/\n\n\K\n+//g;

##</code><code>##

s/(?:\s(?<![ \n]))+/ /g;
s/\n\n\K\n+//g;

##</code><code>##

\s(?<![ \n])

##</code><code>##

[\x{0009}\x{000B}-\x{000D}\x{0085}\x{00A0}\x{1680}\x{180E}\x{2000}-\x{200A}\x{2028}\x{2029}\x{202F}\x{205F}\x{3000}]

##</code><code>##

[\x{0009}\x{000B}-\x{000D}\x{1680}\x{180E}\x{2000}-\x{200A}\x{2028}\x{2029}\x{202F}\x{205F}\x{3000}]