Type for assertion guard functions that narrow input type.
AssertionGuard<T> is a function type that validates input at runtime and
asserts it as type T. Unlike regular assertions that return the value,
assertion guards return void but narrow the input parameter's type.
Type for assertion guard functions that narrow input type.
AssertionGuard<T>is a function type that validates input at runtime and asserts it as typeT. Unlike regular assertions that return the value, assertion guards return void but narrow the input parameter's type.