007 string escape in flow arg

// A string literal with a `\n` (or `\t`) escape is valid Koru — it's just a
// string passed to an event. The parser must NOT reject it as "Zig code in a
// flow". Regression for looksLikeZigCode flagging positional string args with
// escape sequences (`print.ln("a\nb")`) — koruc rejected this with PARSE001
// while `print(text: "a\nb")` (keyed) slipped past. Found via the playground.
~import std/io

~std/io:print.ln("a\nb")