In FOR..ON clauses of PS LOOP, allow :BY to be a number so that the caller can say "(LOOP :for (a b) :on c :by 2..." and doesn't need to invoke a non-Javascripty construct like #'CDDR.
In FOR..ON clauses of PS LOOP, allow :BY to be a number so that the
caller can say "(LOOP :for (a b) :on c :by 2..." and doesn't need to
invoke a non-Javascripty construct like #'CDDR.

fredericksilva/Parenscript,manuel/parenscript,vsedach/Parenscript