try
F=$(fun x, 1)
printvln($F)
println($"Arity of F is $(F.arity)")
if $(not $(eq $(F.arity), 1))
eprintln($"Arity of F is $(F.arity), when 1 was expected")
exit 1
default
eprintln($"Could not compute the arity of a \$(fun) expression")
exit 1
