rb_econv_add_converter 1901 transcode.c        return rb_econv_add_converter(ec, "", decorator_name, n);
rb_econv_add_converter 3195 transcode.c        ret = rb_econv_add_converter(a->ec, sname, dname, a->index);
rb_econv_add_converter 3233 transcode.c                ret = rb_econv_add_converter(ec, sname, dname, ec->num_trans);