/// <summary>
/// Creates an <see cref="IDictionary{TKey, TValue}" /> from an <see cref="IFields" />
/// </summary>
/// <param name="source">An <see cref="IFields" /> to create an <see cref="IDictionary{TKey, TValue}" /> from.</param>
/// <returns>
/// An <see cref="IDictionary{TKey, TValue}" /> that contains the fields from the input source.
/// </returns>
public static IDictionary <string, int> ToDictionary(this IFields source)
{
return(source.ToDictionary(field => field != null));
}