/// <summary>Returns <c>true</c> if the <see cref="Maybe{T}" /> has no value.</summary>
public static bool None <T>(this Maybe <T> maybe) => !maybe.Any();
/// <summary>Expresses an instance of <typeparamref name="T" /> into a <see cref="Maybe{T}" />.</summary>
/// <typeparam name="T">The reference type being wrapped (usually inferred from usage).</typeparam>
/// <param name="source">The source object.</param>
public static Maybe <T> AsMaybe <T>(this T source) where T : class => Maybe <T> .From(source);
