bare7 even more polish

examples/bare7.rs

 //! bare7.rs
-//! 
+//!
 //! Serial echo
 //!
 //! What it covers:
@@ -40,6 +40,7 @@ fn main() -> ! {
 
     let tx = gpioa.pa2.into_alternate_af7();
     let rx = gpioa.pa3.into_alternate_af7(); // try comment out
+                                             
     // let rx = gpioa.pa3.into_alternate_af6(); // try uncomment
 
     let serial = Serial::usart2(
@@ -58,7 +59,7 @@ fn main() -> ! {
         match block!(rx.read()) {
             Ok(byte) => {
                 iprintln!(stim, "Ok {:?}", byte);
-                tx.write(byte).unwrap(); 
+                tx.write(byte).unwrap();
             }
             Err(err) => {
                 iprintln!(stim, "Error {:?}", err);
@@ -94,20 +95,20 @@ fn main() -> ! {
 //    > cargo build --example bare7 --features "stm32fxx-hal"
 //    (or use the vscode build task)
 //
-//    
+//
 //    Cargo.toml:
-// 
+//
 //    [dependencies.stm32f4]
 //    version = "0.5.0"
 //    features = ["stm32f413", "rt"]
 //    optional = true
-// 
+//
 //    [dependencies.stm32f4xx-hal]
 //    version         = "0.6.0"
 //    features        = ["stm32f401", "rt"]
 //    optional        = true
 //
-//    Notice, stm32f4xx-hal internally enables the dependency to stm32f4, 
+//    Notice, stm32f4xx-hal internally enables the dependency to stm32f4,
 //    so we don't need to explicitly enable it.
 //
 //    The HAL provides a generic abstraction over the whole stm32f4 family.
@@ -178,14 +179,14 @@ fn main() -> ! {
 //    Data Bits    8
 //    Stop Bits    1
 //    Parity       None
-//    
+//
 //    This setting is typically abbreviated as 115200 8N1.
 //
 //    Run the example, make sure your ITM is set to 84MHz.
 //
 //    Send a single character (byte), (set the option No end in moserial).
 //    Verify that sent bytes are echoed back, and that ITM tracing is working.
-// 
+//
 //    If not go back check your ITM setting, clocks etc.
 //
 //    Try sending: "abcd" as a single sequence, don't send the quotation marks, just abcd.
@@ -204,7 +205,7 @@ fn main() -> ! {
 //    What did you receive, and what was the output of the ITM trace.
 //
 //    ** your answer here **
-// 
+//
 //    Explain why the buffer overflows.
 //
 //    ** your answer here **
@@ -220,8 +221,8 @@ fn main() -> ! {
 //    The `stm32f4xx-hal` gives you an abstraction for programming,
 //    setting up clocks, assigning pins, etc.
 //
-//    The hal overs basic functionality like serial communication. 
-//    Still, in order to fully understand what is going on under the hood you need to 
+//    The hal overs basic functionality like serial communication.
+//    Still, in order to fully understand what is going on under the hood you need to
 //    check the documentation (data sheets, user manuals etc.)
 //
 //    Your crate can be documented by: