pub(super) fn parse_string_literal(&mut self, s: &str) -> Result<Node, ParseErr> {
        let loc = self.prev_loc();
        let mut s = s.to_string();
        loop {
            match self.peek_no_term()?.kind {
                TokenKind::StringLit(next_s) => {
                    self.get()?;
                    s += &next_s;
                }
                TokenKind::OpenString(next_s, delimiter, level) => {
                    self.get()?;
                    s += &next_s;
                    return self.parse_interporated_string_literal(&s, delimiter, level);
                }
                _ => break,
            }
        }
        Ok(Node::new_string(s, loc))
    }
Parse string literals.
Adjacent string literals are to be combined.
ruruby-parse/src/parser/literals.rs