/// <summary>
/// Associates a member name with a validation rule.
/// </summary>
/// <typeparam name="TTarget"> The type of the target. </typeparam>
/// <typeparam name="TReturn"> The type of the member. </typeparam>
/// <param name="rule"> The rule. </param>
/// <param name="expression"> An expression identifying the member to which the validation rule is associated. </param>
/// <returns> A clone of the source validation rule. </returns>
public static ValidationRule <TTarget> ForMember <TTarget, TReturn>(
this ValidationRule <TTarget> rule,
Expression <Func <TTarget, TReturn> > expression) =>
rule.ForMember(MemberPath.FromExpression(expression));