to_s

static VALUE
fiber_to_s(VALUE fibval)
{
 const rb_fiber_t *fib;
 const rb_proc_t *proc;
 char status_info[0x10];
 GetFiberPtr(fibval, fib);
 snprintf(status_info, 0x10, " (%s)", fiber_status_name(fib->status));
 if (!rb_obj_is_proc(fib->first_proc)) {
 VALUE str = rb_any_to_s(fibval);
 strlcat(status_info, ">", sizeof(status_info));
 rb_str_set_len(str, RSTRING_LEN(str)-1);
 rb_str_cat_cstr(str, status_info);
 return str;
 }
 GetProcPtr(fib->first_proc, proc);
 return rb_block_to_s(fibval, &proc->block, status_info);
}