public void MathExpressionContext_Variable_Declarations_Can_Occur_In_Any_Order()
{
MathExpression expression = MathExpression.Parse("10+x");
MathExpressionContext context = new MathExpressionContext();
context.Define("x", MathExpression.Parse("5y"));
context.Define("y", 3);
double result = expression.Evaluate(context);
Assert.AreEqual(25, result);
}