public async Task <AsyncServerStreamingCall <CounterResponse> > StartAsync(int start)
{
cts = new CancellationTokenSource();
var scopes = _context.GetScopes();
string token = await _tokenProvider.GetTokenAsync(scopes);
var metadataHeaders = new MetadataBuilder().WithToken(token).Build();
return(_client.StartCounter(new CounterRequest {
Start = start
}, metadataHeaders, cancellationToken: cts.Token));
}