read.cs

using LEGO.AsyncAPI.Readers;

// Read the file into a stream
using var filestream = new FileStream("user.yml", FileMode.Open); 

// Create a new AsyncAPI Stream reader and deserialize the file
var document = new AsyncApiStreamReader().Read(filestream, out var diagnostic);  
foreach (var channel in document.Channels)
{
    // Write out any channel keys
    Console.WriteLine(channel.Key); 
}
// Outputs "user/signedup