Function env_to_sexp 

fn env_to_sexp(env: &Environment) -> Sexp

Convert an Environment to an ENVSXP.

Stores a cloned Environment handle (Rc) as a leaked Box in the SEXP’s data pointer. C code can pass this opaque SEXP to Rf_findVar, Rf_defineVar, etc. which extract it via env_from_sexp.