[PD] Abstraction arguments: tell apart symbols from floats from no argument at all

[Peter P.]

* hans w. koch <hansw.koch at gmail.com> [2018-12-22 19:28]:
> i have this vanilla abstraction based on a patch by johannes, which gives 1 for argument present and 0 if absent
> maybe thats for you?

Thanks Hans, this looks good and seems to be a similar way than the one
proposed by Christof.

best, P
> 
> best hans