namespace System.Diagnostics.Metrics
{
    public delegate void MeasurementCallback(Instrument! instrument, T measurement, ReadOnlySpan<KeyValuePair<string!, object?>> tags, object? state)
        where T, struct;
    {
        public virtual IAsyncResult BeginInvoke(Instrument! instrument, T measurement, ReadOnlySpan<KeyValuePair<string!, object?>> tags, object? state, AsyncCallback callback, object object);
    }
}