Handles are low-lewel async I/O objects that perform either reading or writing binary data, or both. Handle-like object is used to construct u8 InputStream and u8 OutputStream.
To create custom I/O handle provide an object that perform any or both of:
async function read(maxSize); // returns Uint8Array or undefied on EOS async function write(uint8ArrayData);
It is a good idea to provide also the u8 source that will take care of constructing custom hanle and return connected stream.