function methodSig () {
  return arrayify(this.params).filter(function (param) {
    return param.name && !/\./.test(param.name);
  }).map(function (param) {
    if (param.variable) {
      return param.optional ? "[..." + param.name + "]" : "..." + param.name;
    } else {
      return param.optional ? "[" + param.name + "]" : param.name;
    }
  }).join(", ");
}
Returns the method signature, e.g. `(options, [onComplete])`
 @this {identifier}
 @returns {string}
 @category Returns string
 @static