Function filter

filter<V>(
    predicate: (
        item: V,
    ) => boolean | Promise<boolean | undefined> | undefined,
): Task<V>
Creates a task filtering stream items based on a predicate.

Items are processed sequentially and output order is preserved.
Type Parameters
- V
  The type of items in the stream
Parameters
- predicate: (item: V) => boolean | Promise<boolean | undefined> | undefined
  The function to test each item. When the predicate returns undefined, it is treated as false and the item is filtered out.
Returns Task<V>
A task that filters items based on the predicate
Remarks
Predicate Composition:

Use predicate utilities from the @metreeca/core predicates module to create complex filtering criteria.
Example
```
await items([1, 2, 3, 4, 5])(filter(x => x % 2 === 0))(toArray());  // [2, 4]
```
- Defined in tasks.ts:183