Implementation in the RestClient.cs and calling from code-behind

multiplefiles.cs

// RestClient.cs
public async Task<Foo> GetPost (int id)
{
    return await _restClient.GetPost (id);
}

// Implementing event to retrieve post 3
private async void Handle_Clicked_Awesome_3 (object sender, System.EventArgs e)
{
    var foo = await _restClient.GetPost (3);

    ResultLabel.Text = $"{foo.id} - {foo.title}";
}