PAIRED_DOUBLE_RE = (prefix, open, close = '\\1') => {
        const middle = (close === '\\1')
          ? close
          : regex.concat(close, open);
        return regex.concat(
          regex.concat("(?:", prefix, ")"),
          open,
          /(?:\\.|[^\\\/])*?/,
          middle,
          /(?:\\.|[^\\\/])*?/,
          close,
          REGEX_MODIFIERS
        );
      }
@param {string|RegExp} prefix
@param {string|RegExp} open
@param {string|RegExp} close