/*
 *   call-seq:
 *      context.suspend -> nil
 *
 *   Suspends the thread when it is running.
 */
static VALUE
context_suspend(VALUE self)
{
    debug_context_t *debug_context;

    debug_check_started();

    Data_Get_Struct(self, debug_context_t, debug_context);
    if(CTX_FL_TEST(debug_context, CTX_FL_SUSPEND))
        rb_raise(rb_eRuntimeError, "Already suspended.");
    context_suspend_0(debug_context);
    return Qnil;
}