code: function pencode(char) {
    var hex = String(char)
      .charCodeAt(0)
      .toString(16)
      .toUpperCase()
    return hex.length === 1
      ? '%0' + hex
      : '%' + hex
  }
docs: Percent encode a single character.
  
  @param {string} char
  @return {string}
  @api private