"""
Simple Calculator Module

Provides basic mathematical operations.
"""


def add(a, b):
    """Add two numbers."""
    return a + b


def subtract(a, b):
    """Subtract b from a."""
    return a - b


def multiply(a, b):
    """Multiply two numbers."""
    return a * b


def divide(a, b):
    """Divide a by b."""
    if b == 0:
        raise ValueError("Cannot divide by zero")
    return a / b


def average(*numbers):
    """
    Calculate the average of a list of numbers.
    
    Args:
        *numbers: Variable number of numeric arguments
        
    Returns:
        float: The average of the input numbers
        
    Raises:
        ValueError: If no numbers are provided
    """
    if len(numbers) == 0:
        raise ValueError("Cannot calculate average of empty list")
    return sum(numbers) / len(numbers)