def add(a, b):
    """Returns the sum of two numbers."""
    return a + b


def subtract(a, b):
    """Returns the difference of two numbers."""
    return a - b


def multiply(a, b):
    """Returns the product of two numbers."""
    return a * b


def divide(a, b):
    """Returns the quotient of two numbers. Raises ValueError on division by zero."""
    if b == 0:
        raise ValueError('Cannot divide by zero')
    return a / b