Definition of classes

    interface Request {
        id: string, // unique identifier of request
        method: string, // REST request method
        header?: Record<string, string>, // map of headers
        url: string,
        body?: string, // UTF-8 encoded into base64 string.
   }

    interface Response {
        id: string, // unique identifier of request (see ***async methods***)
        statusCode: number, // status code from response
        header?: Record<string, string>, // map of headers
        body?: string, // UTF-8 encoded into base64 string.
    }

    interface Save {
        key: string,
        value: string,
    }

    interface Get {
        id: string, // identifier of get (see ***async methods***)
        key: string, // key to value
    }

    interface Get {
        id: string, // identifier of get (see ***async methods***)
        key: string, // key to value
        value?: string // value saved on specific key
    }

    interface SlaveWebView {
        id: string, // identifier of webview
    }

    interface EvaluateJavaScriptSlaveWebView {
        id: string, // identifier of webview
        script: string, // script to evaluate ex. 'window.console.log('hello world');'
    }

    interface LoadPageURLInSlaveWebView {
        id: string, // identifier of webview
        url: string, // url which should be loaded
    }