public static Ensurable <Type> IsAssignableTo <T>(this Ensurable <Type> ensurable, string exceptionMessage = null)
 {
     return(ensurable.IsAssignableTo(typeof(T), exceptionMessage));
 }
 public static Ensurable <Type> IsAssignableTo <T>(this Ensurable <Type> ensurable,
                                                   Func <Ensurable <Type>, Exception> exceptionFactory)
 {
     return(ensurable.IsAssignableTo(typeof(T), exceptionFactory));
 }