WITCH tick: Revision 4
"hard quote", "tick"
Used as a brace pair or quote pair
'' in a bare string literal does minimal interpolation like q//
When used inside regexes
'' chunks multiple gliphs into a single literal as well as escaping metacharacters.
'' around a method name in a call refers to the prefix operator in method postfix form
Old, deprecated, or other language uses
' as a namespace separator as in perl5 is always done with :: in perl6