#[derive(Debug)]
struct AnotherError(i32);

#[derive(Debug)]
struct ContextError(&'static str);

#[derive(Debug)]
enum Error {
    AnotherError { source: AnotherError },

    ContextError { source: ContextError },
}

impl From<AnotherError> for Error {
    fn from(e: AnotherError) -> Self {
        Self::AnotherError { source: e }
    }
}

impl From<ContextError> for Error {
    fn from(e: ContextError) -> Self {
        Self::ContextError { source: e }
    }
}

fn another_fn() -> Result<(), AnotherError> {
    Err(AnotherError(42))
}

fn context_fn() -> Result<(), ContextError> {
    Err(ContextError("oops..."))
}

fn fallible_fn() -> Result<(), Error> {
    another_fn()?;
    context_fn()?;

    Ok(())
}