* and ** demos.

args.py

@@ -0,0 +1,49 @@
+from dataclasses import dataclass
+import json
+import math
+
+
+def mul(init, *args):
+    """Multiply all given arguments.
+
+    >>> mul(3, 3)
+    9
+    >>> mul(3, 3, 3)
+    27
+    """
+    total = init
+    for arg in args:
+        total *= arg  # total = total * arg
+    return total
+
+
+@dataclass
+class Report:
+    date: str
+    current: int
+    last: int
+    total: int
+
+
+api_result = """
+{
+    "date": "2023-12-13",
+    "current": 123,
+    "last": 118,
+    "total": 12
+}
+"""
+
+
+api_data = json.loads(api_result)
+report = Report(**api_data)
+print(report)
+print("Difference:", abs(report.last - report.current))
+
+
+def test_mul():
+    assert mul() == 1
+    assert mul(3) == 3
+    assert mul(2, 3) == 6
+    assert mul(2, 3, 2) == 12
+    assert mul(123456, 654321, 12) == mul(654321, 12, 123456)