Method setHeader

src.ts/utils/fetch.ts:316–318

* Set the header for %%key%% to %%value%%. All values are coerced * to a string.

(key: string, value: string | number)

     *  to a string.
     */
    setHeader(key: string, value: string | number): void {
        this.#headers[String(key).toLowerCase()] = String(value);
    }

    /**
     *  Clear all headers, resetting all intrinsic headers.