Macro vortex_err 

macro_rules! vortex_err {
    (AssertionFailed: $($tts:tt)*) => { ... };
    (IOError: $($tts:tt)*) => { ... };
    (OutOfBounds: $idx:expr, $start:expr, $stop:expr) => { ... };
    (NotImplemented: $func:expr, $by_whom:expr) => { ... };
    (MismatchedTypes: $expected:literal, $actual:expr) => { ... };
    (MismatchedTypes: $expected:expr, $actual:expr) => { ... };
    (Context: $msg:literal, $err:expr) => { ... };
    ($variant:ident: $fmt:literal $(, $arg:expr)* $(,)?) => { ... };
    ($variant:ident: $err:expr $(,)?) => { ... };
    ($fmt:literal $(, $arg:expr)* $(,)?) => { ... };
}

A convenient macro for creating a VortexError.