CHECK_INTEGER     555 iseq.c             version1    = CHECK_INTEGER(rb_ary_entry(data, i++));
CHECK_INTEGER     556 iseq.c             version2    = CHECK_INTEGER(rb_ary_entry(data, i++));
CHECK_INTEGER     557 iseq.c             format_type = CHECK_INTEGER(rb_ary_entry(data, i++));
CHECK_INTEGER     565 iseq.c             first_lineno = CHECK_INTEGER(rb_ary_entry(data, i++));