Pulser Client Problem

[ShrikaKamajdarATS]

I am trying to use the
var client = await PulsarClient.Builder()
.ServiceUrl(new Uri("pulsar://localhost:6650")).Build();

But I am encountering an error: error CS0117: 'PulsarClient' does not contain a definition for 'Builder'. I already have the package installed but I am still encountering the problem.