trickle method
Implementation
void trickle(Trickle trickle) async {
var pc = transports[trickle.target]!.pc;
if (pc != null && transports[trickle.target]!.hasRemoteDescription) {
await pc.addCandidate(trickle.candidate);
} else {
transports[trickle.target]!.candidates.add(trickle.candidate);
}
}