Itertools/takewhile (#42)

* feat(takewhile): implement operation

* chore: apply changeset

.changeset/brown-tables-lay.md

@@ -0,0 +1,5 @@
+---
+"@iter-x/python": patch
+---
+
+implement takewhile operation

packages/python/src/itertools/takewhile.test.ts

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+import { describe, expect, it } from "vitest";
+import { takewhile } from "./takewhile";
+
+describe("takewhile", () => {
+  it("takewhile on empty list", () => {
+    const result = [...takewhile((x) => x < 5, [])];
+    expect(result).toEqual([]);
+  });
+
+  it("takewhile on list", () => {
+    const result = [...takewhile((x) => x < 5, [1, 4, 6, 3, 8])];
+    expect(result).toEqual([1, 4]);
+  });
+});

packages/python/src/itertools/takewhile.ts

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+/**
+ * @example
+ * takewhile((x) => x < 5, [1,4,6,3,8]) -> 1 4
+ */
+export function* takewhile<T>(
+  predicate: (item: T) => boolean,
+  iterable: Iterable<T>,
+): IterableIterator<T> {
+  for (const x of iterable) {
+    if (!predicate(x)) break;
+    yield x;
+  }
+}