How can i write hex decimals to stream ?

i have code like this :

import vibe.d;
import std.stdio;

void run(TCPConnection conn)
{

conn.write(0x00);
conn.write(0x00);
conn.write(0x00);

}

shared static this()
{

listenTCP(3724, (conn) => run(conn));

}

thhis will give me an error, no write's callable with arguments