if anyone’s in the mood for code review, I’d be curious to know if there’s a neater way of doing this, which works fine but smells bad
```rust
/// Convert 12-bit signed integer within a 4 byte long buffer into 16-bit signed integer.
fn a1454_buf_to_i16(buffer: &[u8; 4]) -> i16 {
    let lower = buffer[3];
    let mut upper = buffer[2];
    // Fill in additional 1s if the 12 bit number is negative.
    if (upper & 0b00001000) == 0b0001000 {
        upper = upper | 0b11110000;
    }

    let mut sensor_value_raw: u16 = lower.into();
    sensor_value_raw |= (upper as u16) << 8;
    let sensor_value: u16 = sensor_value_raw.into();
    let sensor_value = sensor_value as i16;
    sensor_value
}
```
afaik `from_*e_bytes` won’t work as I need to check the sign of the 12-bit number inside the buffer, and extend the leading 1s if it’s negative