#700 - Allow for missing optional containers snabb set
#700 - Allow for missing optional containers snabb set

This allows you to miss out optional arguments where there is a
container without any required leaves in it. Previous you would often
get a casting error when they were left empty of omitted.

dpino/snabbswitch,SnabbCo/snabbswitch,Igalia/snabb,eugeneia/snabb,heryii/snabb,Igalia/snabb,snabbco/snabb,dpino/snabb,heryii/snabb,alexandergall/snabbswitch,snabbco/snabb,Igalia/snabbswitch,eugeneia/snabb,alexandergall/snabbswitch,SnabbCo/snabbswitch,eugeneia/snabb,Igalia/snabbswitch,alexandergall/snabbswitch,alexandergall/snabbswitch,eugeneia/snabbswitch,eugeneia/snabb,dpino/snabb,dpino/snabb,heryii/snabb,dpino/snabb,Igalia/snabbswitch,snabbco/snabb,alexandergall/snabbswitch,dpino/snabb,snabbco/snabb,dpino/snabb,eugeneia/snabb,Igalia/snabb,Igalia/snabb,eugeneia/snabbswitch,dpino/snabbswitch,eugeneia/snabb,eugeneia/snabb,SnabbCo/snabbswitch,alexandergall/snabbswitch,Igalia/snabb,Igalia/snabb,dpino/snabbswitch,snabbco/snabb,snabbco/snabb,eugeneia/snabb,snabbco/snabb,eugeneia/snabbswitch,dpino/snabbswitch,heryii/snabb,Igalia/snabbswitch,SnabbCo/snabbswitch,snabbco/snabb,dpino/snabb,heryii/snabb,heryii/snabb,Igalia/snabbswitch,eugeneia/snabbswitch,alexandergall/snabbswitch,Igalia/snabb,alexandergall/snabbswitch,Igalia/snabb