Function Rf_lang3 

pub unsafe fn Rf_lang3(s: SEXP, t: SEXP, u: SEXP) -> SEXP

Build a language object (call) with function and 2 arguments.

Rust equivalent of R’s inline Rf_lang3(s, t, u). Creates a call like f(arg1, arg2).

Safety

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