/// <summary>
      /// Apply an "equal" constraint to the named property
      /// </summary>
      /// <param name="propertyName">The name of the Property in the class.</param>
      /// <param name="value">The value for the Property.</param>
      /// <returns>An <see cref="EqExpression" />.</returns>
      public static SimpleExpression Eq(string propertyName, object value)
      {
         return new EqExpression(propertyName, value);
      }