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    use core::ops::{Add, Sub, Mul, Div, Shl, Shr};

    /// Performs addition that returns `None` instead of wrapping around on
    /// overflow.
    pub trait CheckedAdd: Sized + Add<Self, Output=Self> {
        /// Adds two numbers, checking for overflow. If overflow happens, `None` is
        /// returned.
        fn checked_add(&self, v: &Self) -> Option<Self>;
    }

    macro_rules! checked_impl {
        ($trait_name:ident, $method:ident, $t:ty) => {
            impl $trait_name for $t {
                #[inline]
                fn $method(&self, v: &$t) -> Option<$t> {
                    <$t>::$method(*self, *v)
                }
            }
        }
    }

    checked_impl!(CheckedAdd, checked_add, u8);
    checked_impl!(CheckedAdd, checked_add, u16);
    checked_impl!(CheckedAdd, checked_add, u32);
    checked_impl!(CheckedAdd, checked_add, u64);
    checked_impl!(CheckedAdd, checked_add, usize);

    checked_impl!(CheckedAdd, checked_add, i8);
    checked_impl!(CheckedAdd, checked_add, i16);
    checked_impl!(CheckedAdd, checked_add, i32);
    checked_impl!(CheckedAdd, checked_add, i64);
    checked_impl!(CheckedAdd, checked_add, isize);

    /// Performs subtraction that returns `None` instead of wrapping around on underflow.
    pub trait CheckedSub: Sized + Sub<Self, Output=Self> {
        /// Subtracts two numbers, checking for underflow. If underflow happens,
        /// `None` is returned.
        fn checked_sub(&self, v: &Self) -> Option<Self>;
    }

    checked_impl!(CheckedSub, checked_sub, u8);
    checked_impl!(CheckedSub, checked_sub, u16);
    checked_impl!(CheckedSub, checked_sub, u32);
    checked_impl!(CheckedSub, checked_sub, u64);
    checked_impl!(CheckedSub, checked_sub, usize);

    checked_impl!(CheckedSub, checked_sub, i8);
    checked_impl!(CheckedSub, checked_sub, i16);
    checked_impl!(CheckedSub, checked_sub, i32);
    checked_impl!(CheckedSub, checked_sub, i64);
    checked_impl!(CheckedSub, checked_sub, isize);

    /// Performs multiplication that returns `None` instead of wrapping around on underflow or
    /// overflow.
    pub trait CheckedMul: Sized + Mul<Self, Output=Self> {
        /// Multiplies two numbers, checking for underflow or overflow. If underflow
        /// or overflow happens, `None` is returned.
        fn checked_mul(&self, v: &Self) -> Option<Self>;
    }

    checked_impl!(CheckedMul, checked_mul, u8);
    checked_impl!(CheckedMul, checked_mul, u16);
    checked_impl!(CheckedMul, checked_mul, u32);
    checked_impl!(CheckedMul, checked_mul, u64);
    checked_impl!(CheckedMul, checked_mul, usize);

    checked_impl!(CheckedMul, checked_mul, i8);
    checked_impl!(CheckedMul, checked_mul, i16);
    checked_impl!(CheckedMul, checked_mul, i32);
    checked_impl!(CheckedMul, checked_mul, i64);
    checked_impl!(CheckedMul, checked_mul, isize);

    /// Performs division that returns `None` instead of panicking on division by zero and instead of
    /// wrapping around on underflow and overflow.
    pub trait CheckedDiv: Sized + Div<Self, Output=Self> {
        /// Divides two numbers, checking for underflow, overflow and division by
        /// zero. If any of that happens, `None` is returned.
        fn checked_div(&self, v: &Self) -> Option<Self>;
    }

    checked_impl!(CheckedDiv, checked_div, u8);
    checked_impl!(CheckedDiv, checked_div, u16);
    checked_impl!(CheckedDiv, checked_div, u32);
    checked_impl!(CheckedDiv, checked_div, u64);
    checked_impl!(CheckedDiv, checked_div, usize);

    checked_impl!(CheckedDiv, checked_div, i8);
    checked_impl!(CheckedDiv, checked_div, i16);
    checked_impl!(CheckedDiv, checked_div, i32);
    checked_impl!(CheckedDiv, checked_div, i64);
    checked_impl!(CheckedDiv, checked_div, isize);

    /// Performs a left shift that returns `None` on overflow.
    pub trait CheckedShl: Sized + Shl<u32, Output=Self> {
        /// Shifts a number to the left, checking for overflow. If overflow happens,
        /// `None` is returned.
        ///
        /// ```
        /// use num_traits::CheckedShl;
        ///
        /// let x: u16 = 0x0001;
        ///
        /// assert_eq!(CheckedShl::checked_shl(&x, 0),  Some(0x0001));
        /// assert_eq!(CheckedShl::checked_shl(&x, 1),  Some(0x0002));
        /// assert_eq!(CheckedShl::checked_shl(&x, 15), Some(0x8000));
        /// assert_eq!(CheckedShl::checked_shl(&x, 16), None);
        /// ```
        fn checked_shl(&self, rhs: u32) -> Option<Self>;
    }

    macro_rules! checked_shift_impl {
        ($trait_name:ident, $method:ident, $t:ty) => {
            impl $trait_name for $t {
                #[inline]
                fn $method(&self, rhs: u32) -> Option<$t> {
                    <$t>::$method(*self, rhs)
                }
            }
        }
    }

    checked_shift_impl!(CheckedShl, checked_shl, u8);
    checked_shift_impl!(CheckedShl, checked_shl, u16);
    checked_shift_impl!(CheckedShl, checked_shl, u32);
    checked_shift_impl!(CheckedShl, checked_shl, u64);
    checked_shift_impl!(CheckedShl, checked_shl, usize);

    checked_shift_impl!(CheckedShl, checked_shl, i8);
    checked_shift_impl!(CheckedShl, checked_shl, i16);
    checked_shift_impl!(CheckedShl, checked_shl, i32);
    checked_shift_impl!(CheckedShl, checked_shl, i64);
    checked_shift_impl!(CheckedShl, checked_shl, isize);

    /// Performs a right shift that returns `None` on overflow.
    pub trait CheckedShr: Sized + Shr<u32, Output=Self> {
        /// Shifts a number to the left, checking for overflow. If overflow happens,
        /// `None` is returned.
        ///
        /// ```
        /// use num_traits::CheckedShr;
        ///
        /// let x: u16 = 0x8000;
        ///
        /// assert_eq!(CheckedShr::checked_shr(&x, 0),  Some(0x8000));
        /// assert_eq!(CheckedShr::checked_shr(&x, 1),  Some(0x4000));
        /// assert_eq!(CheckedShr::checked_shr(&x, 15), Some(0x0001));
        /// assert_eq!(CheckedShr::checked_shr(&x, 16), None);
        /// ```
        fn checked_shr(&self, rhs: u32) -> Option<Self>;
    }

    checked_shift_impl!(CheckedShr, checked_shr, u8);
    checked_shift_impl!(CheckedShr, checked_shr, u16);
    checked_shift_impl!(CheckedShr, checked_shr, u32);
    checked_shift_impl!(CheckedShr, checked_shr, u64);
    checked_shift_impl!(CheckedShr, checked_shr, usize);

    checked_shift_impl!(CheckedShr, checked_shr, i8);
    checked_shift_impl!(CheckedShr, checked_shr, i16);
    checked_shift_impl!(CheckedShr, checked_shr, i32);
    checked_shift_impl!(CheckedShr, checked_shr, i64);
    checked_shift_impl!(CheckedShr, checked_shr, isize);

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