/// <summary>
/// Recusively decompose an expression into a tree of ExpressionElements
/// </summary>
/// <param name="expressionElement"></param>
/// <param name="level"></param>
/// <returns>The ExpressionElement with the SubExpressionElements property populated</returns>
private ExpressionElement Decompose(ExpressionElement expressionElement, int level = 0)
{
IEnumerable<ExpressionElement> expressionElementChildren
= FindExpressionsAtSameLevel(expressionElement.Expression, level);
expressionElement.PopulateSubExpressionElements(expressionElementChildren.Select(e => Decompose(e, level + 1)));
return expressionElement;
}