Transfers bytes to the stream, calling drain as many times as necessary
such that all bytes are transferred.
See also:
printwriteVecAllwritepub fn writeAll(w: *Writer, bytes: []const u8) Error!void
pub fn writeAll(w: *Writer, bytes: []const u8) Error!void {
var index: usize = 0;
while (index < bytes.len) index += try w.write(bytes[index..]);
}