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export default class SwarmGate {  constructor(    public readonly host: string,  ) {}
  //TODO  //Check if hash is valid  async download(hash: string): Promise<Uint8Array> {    return fetch(`${this.host}/bzz-raw:/${hash}`)      .then((response) => {        if (response.ok) {          return response.arrayBuffer()            .then((x) => new Uint8Array(x));        }        throw new Error(`Request failed with status ${response.status}`);      });  }
  //TODO  //There must be a better way to check swarm node availability  async isAvailable(): Promise<boolean> {    return !!await this.upload(new Uint8Array([1]));  }
  async upload(file: Uint8Array): Promise<string> {    if (!(file instanceof Uint8Array)) {      throw new Error("The data to upload must be an Uint8Array data set");    }    if (file.length === 0) {      throw new Error("The data to upload can't be an empty data set");    }
    return fetch(`${this.host}/bzz-raw:`, {      body: file,      method: "POST",    })      .then((response) => {        if (response.ok) {          return response.text();        }        throw new Error(`Request failed with status ${response.status}`);      });  }}