I also like how Raku has extended this with the Q operator, allowing one to specify what should be interpolated (scalars, escape sequences, closures, etc) also with arbitrary delimiters --
Q/I got $5 \sigh / # literal
Q:s/Hello $name/ # just scalars
Q:b/hello world\n/ # just backslash escape sequences
Raku supports leap seconds. see https://docs.raku.org/type/Instant