Change
2->var1{1}
to
2->var1[1]
or
{2}->var1
Because [] brackets signify the element of a matrix or list when used
after the variable name, but {} brackets are used only to make a list.
> If var1={0} Then
> 2->var1{1}
> Else
> augment(var1,{2})->var1
> EndIf