#[stable(feature = "std_debug", since = "1.16.0")]
impl<'a, T: ?Sized + fmt::Debug> fmt::Debug for MutexGuard<'a, T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
#[stable(feature = "std_debug", since = "1.16.0")]
impl<'a, T: ?Sized + fmt::Debug> fmt::Debug for MutexGuard<'a, T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {