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The compiler supports this now.  We can type less going forward.
No functional changes.

Signed-off-by: Stephan Pleines <pleines.stephan@gmail.com>
Change-Id: I29d6fa4f9aacc0e381f1a7637294db0392466995
diff --git a/frc971/wpilib/spi_rx_clearer.cc b/frc971/wpilib/spi_rx_clearer.cc
index 1faa3f6..09bbbc8 100644
--- a/frc971/wpilib/spi_rx_clearer.cc
+++ b/frc971/wpilib/spi_rx_clearer.cc
@@ -8,8 +8,7 @@
 
 #include "aos/logging/logging.h"
 
-namespace frc971 {
-namespace wpilib {
+namespace frc971::wpilib {
 
 SpiRxClearer::SpiRxClearer() {
   const int fd = AOS_PCHECK(open("/dev/mem", O_RDWR));
@@ -40,5 +39,4 @@
   AOS_LOG(FATAL, "Failed to clear the RX FIFO\n");
 }
 
-}  // namespace wpilib
-}  // namespace frc971
+}  // namespace frc971::wpilib