Item Property

Gets a part based on its position index. This is the indexer for the class.

[Visual Basic]
Public Default ReadOnly Property Item( _
ByVal part As Integer _
) As Expr

[C#]
public Expr this[
int part
] {get;}

Part numbers are just like in Mathematica: 0 gives the head, and arguments are counted from 1 onward.

Exception Type	Condition
IndexOutOfRangeException	If the part index is greater than the number of arguments.

Expr.Item Property