refactor: Minor optimization, remove return keyword.

src/Operation/Chunk.php

@@ -53,7 +53,7 @@ static function (Iterator $iterator) use ($sizes): Generator {
                         $size = $sizesIterator->current();
 
                         if (0 >= $size) {
-                            return new EmptyIterator();
+                            return yield [];
                         }
 
                         if (count($values) !== $size) {
@@ -69,7 +69,7 @@ static function (Iterator $iterator) use ($sizes): Generator {
                         $values = [$value];
                     }
 
-                    return yield $values;
+                    yield $values;
                 };
     }
 }

src/Operation/Equals.php

@@ -56,7 +56,7 @@ static function (Iterator $other): Closure {
                          */
                         static fn ($current): bool => (new Contains())()($current)($other)->current();
 
-                    return yield from (new Every())()(static fn (): bool => false)($containsCallback)($iterator);
+                    yield from (new Every())()(static fn (): bool => false)($containsCallback)($iterator);
                 };
             };
     }

src/Operation/Head.php

@@ -24,31 +24,28 @@ final class Head extends AbstractOperation
     /**
      * @pure
      *
-     * @return Closure(Iterator<TKey, T>): Generator<TKey, T>
+     * @return Closure(Iterator<TKey, T>): Generator<TKey, T, mixed, void>
      */
     public function __invoke(): Closure
     {
         return
             /**
              * @param Iterator<TKey, T> $iterator
              *
-             * @return Generator<TKey, T>
+             * @return Generator<TKey, T, mixed, void>
              */
             static function (Iterator $iterator): Generator {
                 $isEmpty = true;
 
+                $key = $current = null;
                 foreach ($iterator as $key => $current) {
                     $isEmpty = false;
 
                     break;
                 }
 
                 if (false === $isEmpty) {
-                    /**
-                     * @var TKey $key
-                     * @var T $current
-                     */
-                    return yield $key => $current;
+                    yield $key => $current;
                 }
             };
     }

src/Operation/Last.php

@@ -37,16 +37,13 @@ public function __invoke(): Closure
             static function (Iterator $iterator): Generator {
                 $isEmpty = true;
 
+                $key = $current = null;
                 foreach ($iterator as $key => $current) {
                     $isEmpty = false;
                 }
 
                 if (false === $isEmpty) {
-                    /**
-                     * @var TKey $key
-                     * @var T $current
-                     */
-                    return yield $key => $current;
+                    yield $key => $current;
                 }
             };
     }

src/Operation/Pack.php

@@ -39,7 +39,7 @@ static function (Iterator $iterator): Generator {
                 /** @var PackIterableAggregate<TKey, T> $packIterableAggregate */
                 $packIterableAggregate = new PackIterableAggregate($iterator);
 
-                return yield from $packIterableAggregate->getIterator();
+                yield from $packIterableAggregate->getIterator();
             };
     }
 }

src/Operation/Same.php

@@ -58,7 +58,7 @@ static function (Iterator $iterator) use ($other, $comparatorCallback): Generato
                             $other->next();
                         }
 
-                        return yield $iterator->valid() === $other->valid();
+                        yield $iterator->valid() === $other->valid();
                     };
     }
 }

src/Operation/Tails.php

@@ -49,7 +49,7 @@ static function (Iterator $iterator): Generator {
                     array_shift($data);
                 }
 
-                return yield [];
+                yield [];
             };
     }
 }