def greet(name, greeting="Xin chào"):
    return f"{greeting}, {name}!"

print(greet("Python"))  # Xin chào, Python!
print(greet("Python", "Chào"))  # Chào, Python!

def sum_all(*args):
    total = 0
    for num in args:
        total += num
    return total

print(sum_all(1, 2, 3, 4, 5))  # 15

def print_info(**kwargs):
    for key, value in kwargs.items():
        print(f"{key}: {value}")

print_info(name="Python", age=30)

square = lambda x: x ** 2
print(square(5))  # 25

numbers = [1, 2, 3, 4, 5]
squared = list(map(lambda x: x ** 2, numbers))
print(squared)  # [1, 4, 9, 16, 25]

import math
print(math.sqrt(16))  # 4.0

from math import sqrt, pi
print(sqrt(25))  # 5.0
print(pi)  # 3.141592653589793

def add(a, b):
    return a + b

def multiply(a, b):
    return a * b

import utils
result = utils.add(5, 3)
print(result)  # 8

with open('data.txt', 'r') as f:
    content = f.read()
    print(content)

with open('output.txt', 'w') as f:
    f.write("Hello, Python!")

with open('data.txt', 'r') as f:
    for line in f:
        print(line.strip())