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/** * If A extends B, returns Then (default true) or else Else (default false) * @example * ```ts * Extends<1, number> => true * Extends<1, string> => false * Extends<1, number, 'a', 'b'> => 'a' * Extends<1, string, 'a', 'b'> => 'b' * ``` */export type Extends<A, B, Then = true, Else = false> = A extends B  ? Then  : Else;
/** * If A does not extend B, returns Then (default true) or else Else (default false) * @example * ```ts * NotExtends<1, number> => false * NotExtends<1, string> => true * NotExtends<1, number, 'a', 'b'> => 'b' * NotExtends<1, string, 'a', 'b'> => 'a' * ``` */export type NotExtends<A, B, Then = true, Else = false> = A extends B  ? Else  : Then;
/** * Returns never if the given type is false, otherwise unknown. * @example * ```ts * Check<IsEven<4>> => unknown * Check<IsEven<5>> => never * ``` */export type Check<V> = V extends false ? never : unknown;
/** * Returns never if the given type is false, otherwise true. * @example * ```ts * Validate<IsEven<4>> => true * Validate<IsEven<5>> => never * ``` */export type Validate<V> = V extends false ? never : true;
/** * Returns false is the given type is false, true otherwise. * @example * ```ts * Pred<false> => false * Pred<number> => true * Pred<true> => true * ``` */export type Pred<V> = V extends false ? false : true;
/** * Returns true if the input type is false, and false if the input type is true. * @example * ```ts * Not<true> => false * Not<false> => true * Not<boolean> => never * ``` */export type Not<V extends boolean> = boolean extends V  ? never  : V extends true  ? false  : true;