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import { IParser, OnParse } from "./interfaces.ts";
export class GuardParser<A, B> implements IParser<A, B> {  constructor(    readonly checkIsA: (value: A) => value is A & B,    readonly typeName: string,    readonly description = {      name: "Guard",      children: [],      extras: [typeName],    } as const,  ) {}  parse<C, D>(a: A, onParse: OnParse<A, B, C, D>): C | D {    if (this.checkIsA(a)) {      return onParse.parsed(a);    }    return onParse.invalid({      value: a,      keys: [],      parser: this,    });  }}