Function isNotString

isNotString<T>(u: T): u is RelaxedExclude<T, string>
Type guard that checks if a value is not a string.

Type Narrowing Behavior:
- Excludes string from the input type when true
- Preserves all other types in the union
Type Parameters
- T
  The type of the input value
Parameters
- u: T
  The value to check
Returns u is RelaxedExclude<T, string>
true if u is not a string, false otherwise. When true, TypeScript excludes string from the type.
Example
```
const values: unknown[] = ['Ada', 42, 'Lovelace'];

const nonStrings = values.filter(isNotString);

assert.deepStrictEqual(nonStrings, [42]);
```
- Defined in src/guard/is-type.mts:251