Function Rf_list3 

pub unsafe fn Rf_list3(s: SEXP, t: SEXP, u: SEXP) -> SEXP

Build a pairlist with 3 elements.

Rust equivalent of R’s inline Rf_list3(s, t, u).

Safety

• All SEXPs must be valid
• Must be called from R’s main thread
• Result must be protected from GC