Function erlang_nif_sys::erlang_nif_sys_api::enif_get_list_cell

pub unsafe extern "C" fn enif_get_list_cell(
    env: *mut ErlNifEnv, 
    term: ERL_NIF_TERM, 
    head: *mut ERL_NIF_TERM, 
    tail: *mut ERL_NIF_TERM
) -> c_int

See enif_get_list_cell in the Erlang docs.