f, 1 argument:
f, 2 arguments:
Evaluating param opt1 to Syntactic_arity.f.
Evaluating param opt2 to Syntactic_arity.f.
f_lazy, 1 argument:
f_lazy, 2 arguments:
Evaluating param opt1 to Syntactic_arity.f_lazy.
Evaluating param opt2 to Syntactic_arity.f_lazy.