Testing metacharacter operations.
\L: [BAR] => [bar]
\U: [bar] => [BAR]
\l: [BAR] => [bAR]
\u: [bar] => [Bar]

Testing function operations.
     lc(BAR) => (bar)
     uc(bar) => (BAR)
lcfirst(BAR) => (bAR)
ucfirst(bar) => (Bar)