Constant BYNK_STRING_SRC 

pub const BYNK_STRING_SRC: &'static str;

bynk.string — Bynk-written helpers over the v0.22a string kernel (concat, the List fold, and the Option kernel methods). The kernel itself is compiler built-in (ADR 0046); only derived helpers live here. join folds to Option[String] so empty-string elements are joined faithfully (a bare "" accumulator could not tell “nothing yet” from “first element was empty”).