code: function atext() {
          return wrap('atext', compareToken(function atextFunc(tok) {
              var accept =
                  ('a' <= tok && tok <= 'z') ||
                  ('A' <= tok && tok <= 'Z') ||
                  ('0' <= tok && tok <= '9') ||
                  (['!', '#', '$', '%', '&', '\'', '*', '+', '-', '/',
                    '=', '?', '^', '_', '`', '{', '|', '}', '~'].indexOf(tok) >= 0);
              if (opts.rfc6532) {
                  accept = accept || isUTF8NonAscii(tok);
              }
              return accept;
          }));
      }
docs: atext           =   ALPHA / DIGIT /    ; Printable US-ASCII "!" / "#" /        ;  characters not including "$" / "%" /        ;  specials.  Used for atoms. "&" / "'" / "*" / "+" / "-" / "/" / "=" / "?" / "^" / "_" / "`" / "{" / "|" / "}" / "~"