this is what happens

```
 ❯ cargo embed --target thumbv7em-none-eabihf
   Compiling led-compass v0.1.0 (/var/home/sashin/ドキュメント/projects/rust-microbit/discovery-master/microbit/src/09-led-compass)
   Compiling led-roulette v0.1.0 (/var/home/sashin/ドキュメント/projects/rust-microbit/discovery-master/microbit/src/05-led-roulette)
   Compiling punch-o-meter v0.1.0 (/var/home/sashin/ドキュメント/projects/rust-microbit/discovery-master/microbit/src/10-punch-o-meter)
   Compiling uart v0.1.0 (/var/home/sashin/ドキュメント/projects/rust-microbit/discovery-master/microbit/src/07-uart)
   Compiling i2c v0.1.0 (/var/home/sashin/ドキュメント/projects/rust-microbit/discovery-master/microbit/src/08-i2c)
error: could not compile `led-roulette` (bin "led-roulette") due to 2 previous errors
warning: build failed, waiting for other jobs to finish...
error: could not compile `punch-o-meter` (bin "punch-o-meter") due to 2 previous errors
error: could not compile `i2c` (bin "i2c") due to 5 previous errors
error: could not compile `uart` (bin "uart") due to 4 previous errors
error: could not compile `led-compass` (bin "led-compass") due to 5 previous errors
error[E0433]: failed to resolve: use of undeclared crate or module `microbit`
 --> src/08-i2c/src/main.rs:9:5
  |
9 | use microbit::hal::prelude::*;
  |     ^^^^^^^^ use of undeclared crate or module `microbit`

error[E0432]: unresolved import `microbit`
 --> src/05-led-roulette/src/main.rs:7:5
  |
7 | use microbit as _;
  |     ^^^^^^^^^^^^^ no external crate `microbit`

error[E0433]: failed to resolve: use of undeclared crate or module `microbit`
  --> src/10-punch-o-meter/src/main.rs:12:17
   |
12 |     let board = microbit::Board::take().unwrap();
   |                 ^^^^^^^^ use of undeclared crate or module `microbit`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0432`.
error[E0433]: failed to resolve: use of undeclared crate or module `microbit`
  --> src/09-led-compass/src/calibration.rs:11:5
   |
11 | use microbit::display::blocking::Display;
   |     ^^^^^^^^ use of undeclared crate or module `microbit`

error[E0433]: failed to resolve: use of undeclared crate or module `microbit`
  --> src/09-led-compass/src/main.rs:13:5
   |
13 | use microbit::{display::blocking::Display, hal::Timer};
   |     ^^^^^^^^ use of undeclared crate or module `microbit`

error[E0433]: failed to resolve: use of undeclared crate or module `microbit`
  --> src/08-i2c/src/main.rs:32:17
   |
32 |     let board = microbit::Board::take().unwrap();
   |                 ^^^^^^^^ use of undeclared crate or module `microbit`

error[E0425]: cannot find value `i2c` in this scope
  --> src/08-i2c/src/main.rs:45:5
   |
45 |     i2c.write_read(ACCELEROMETER_ADDR, &[ACCELEROMETER_ID_REG], &mut acc).unw...
   |     ^^^ not found in this scope

error[E0425]: cannot find value `i2c` in this scope
  --> src/08-i2c/src/main.rs:46:5
   |
46 |     i2c.write_read(MAGNETOMETER_ADDR, &[MAGNETOMETER_ID_REG], &mut mag).unwra...
   |     ^^^ not found in this scope

error[E0433]: failed to resolve: use of undeclared crate or module `microbit`
  --> src/07-uart/src/main.rs:30:17
   |
30 |     let board = microbit::Board::take().unwrap();
   |                 ^^^^^^^^ use of undeclared crate or module `microbit`

error[E0425]: cannot find value `serial` in this scope
  --> src/07-uart/src/main.rs:53:16
   |
53 |     nb::block!(serial.write(b'X')).unwrap();
   |                ^^^^^^ not found in this scope

error[E0425]: cannot find value `serial` in this scope
  --> src/07-uart/src/main.rs:54:16
   |
54 |     nb::block!(serial.flush()).unwrap();
   |                ^^^^^^ not found in this scope

error: aborting due to previous error

For more information about this error, try `rustc --explain E0433`.
error: aborting due to 4 previous errors

Some errors have detailed explanations: E0425, E0433.
For more information about an error, try `rustc --explain E0425`.
error[E0433]: failed to resolve: use of undeclared crate or module `microbit`
  --> src/09-led-compass/src/main.rs:26:17
   |
26 |     let board = microbit::Board::take().unwrap();
   |                 ^^^^^^^^ use of undeclared crate or module `microbit`

error[E0425]: cannot find value `i2c` in this scope
  --> src/09-led-compass/src/main.rs:37:46
   |
37 |     let mut sensor = Lsm303agr::new_with_i2c(i2c);
   |                                              ^^^ not found in this scope

error: aborting due to 3 previous errors

Some errors have detailed explanations: E0425, E0433.
For more information about an error, try `rustc --explain E0425`.
error: aborting due to 4 previous errors

Some errors have detailed explanations: E0425, E0433.
For more information about an error, try `rustc --explain E0425`.
       Error Failed to run cargo build: exit code = Some(101).

```