pub trait AlmostEqual {
    fn almost_equal(&self, other: &Self) -> bool;
}

// Modified version of the original assert_eq implementation from
// https://github.com/rust-lang/rust/blob/909f5a049415a815b23502a5498de9a99bbf276b/src/libcore/macros.rs
#[macro_export]
macro_rules! assert_almost_eq {
    ($left:expr, $right:expr) => ({
        match (&$left, &$right) {
            (left_val, right_val) => {
                if !((*left_val).almost_equal(right_val)) {
                    // The reborrows below are intentional. Without them, the stack slot for the
                    // borrow is initialized even before the values are compared, leading to a
                    // noticeable slow down.
                    panic!(r#"assertion failed: `(left.almost_equal(right))`
  left: `{:?}`,
 right: `{:?}`"#, &*left_val, &*right_val)
                }
            }
        }
    });
    ($left:expr, $right:expr,) => ({
        assert_almost_eq!($left, $right)
    });
    ($left:expr, $right:expr, $($arg:tt)+) => ({
        match (&($left), &($right)) {
            (left_val, right_val) => {
                if !((*left_val).almost_equal(right_val)) {
                    // The reborrows below are intentional. Without them, the stack slot for the
                    // borrow is initialized even before the values are compared, leading to a
                    // noticeable slow down.
                    panic!(r#"assertion failed: `(left.almost_equal(right))`
  left: `{:?}`,
 right: `{:?}`: {}"#, &*left_val, &*right_val,
                           format_args!($($arg)+))
                }
            }
        }
    });
}