Function builtin_formals_set 

fn builtin_formals_set(
    args: &[RValue],
    _: &[(String, RValue)],
) -> Result<RValue, RError>

formals<-(fn, value) — set the formals of a closure.

@param fn function whose formals to replace @param value new formals as a pairlist/list @return modified function @namespace base