[Feature request] Yup-like shotcut methods in the main z object

[LonguCodes]

Currenty, the only way to create a shortcut is to create a function and wrap the schema inside it.

function emptyOrOptional(schema: ZodString): ZodString {
   return z.union([schema.optional(), z.string().max(0)]);
}

const validationSchema = emptyOrOptional(z.string().email())

This results in 2 different sytanxes, chaining and wrapping.

Would it be possible to create something similar to yup's addMethod, which would result in following code?

z.addMethod('emptyOrOptional',<params>);

const validationSchema = z.string().email().emptyOrOptional()

[LonguCodes]

This is achievable using typescript and some prototype pollution

// zod-custom.d.ts

export * from 'zod';
declare module 'zod' {
  interface ZodString {
    allowEmpty(): ZodString;
  }
}

// zod-custom.ts

import { z, ZodString } from 'zod';

z.ZodString.prototype['allowEmpty'] = function () {
  return this.or(z.string().max(0)) as unknown as ZodString;
};

Maybe documentation would be enough in this case