/// <summary>
/// Searches for the specified element.
/// </summary>
/// <typeparam name="T">Type of elements stored in the relation</typeparam>
/// <param name="rel">Unary relation</param>
/// <param name="x">Element to look for</param>
/// <returns>Sequence of occurences (either empty or containing exactly one element)</returns>
public static IEnumerable <T> Find <T>(this ImmutableRelation <T> rel, T?x)
where T : struct
{
return(rel.Find(x == null ? ItemMatcher <T> .Any : new ItemMatcher <T>(x.Value)));
}
/// <summary>
/// Searches for the specified element.
/// </summary>
/// <typeparam name="T">Type of elements stored in the relation</typeparam>
/// <param name="rel">Unary relation</param>
/// <param name="x">Element to look for</param>
/// <returns>Sequence of occurences (either empty or containing exactly one element)</returns>
public static IEnumerable <T> Find <T>(this ImmutableRelation <T> rel, T x)
where T : class
{
return(rel.Find(x == null ? ItemMatcher <T> .Any : new ItemMatcher <T>(x)));
}
