Function checked_try_from_sexp_i64 

pub fn checked_try_from_sexp_i64(sexp: SEXP, param: &str) -> i64

Convert R SEXP to i64 in strict mode.

Only INTSXP and REALSXP are accepted. RAWSXP and LGLSXP are rejected. For REALSXP, uses TryCoerce to reject fractional, NaN, and out-of-range values.