* I thought to do something like this:
```
#[derive(Debug)]
enum BusPinErrorKind {
    SetLow(ErrorKind),
    SetHigh(ErrorKind),
    IsHigh(ErrorKind),
}

impl fmt::Display for BusPinErrorKind {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::SetLow(_) => write!(f, "could not set pin low"),
            Self::SetHigh(_) => write!(f, "could not set pin high"),
            Self::IsHigh(_) => write!(f, "could not read pin"),
        }
    }
}

impl Error for BusPinErrorKind {
    fn source(&self) -> Option<&(dyn Error + 'static)> {
        match &self {
            Self::SetLow(error) => Some(error),
            Self::SetHigh(error) => Some(error),
            Self::IsHigh(error) => Some(error),
        }
    }
}
```
And then if the set_high() returns an error variant I store that ErrorKind in my Error and then create a stack trace to the top.