SCM_ASSERT_TYPE (scm_ilength (rods) > 0, rods, SCM_ARG1, __FUNCTION__, "list of rods");
LY_ASSERT_TYPE (scm_is_number, length, 3);
SCM_ASSERT_TYPE (scm_ilength (rods) > 0, rods, SCM_ARG1, __FUNCTION__, "list of rods");
LY_ASSERT_TYPE (scm_is_number, length, 3);