def add(a: float, b: float) -> float:
    """Add two numbers.
    
    Args:
        a: first float
        b: second float

    Returns:
        Result float
    """
    return a + b

def subtract(a: float, b: float) -> float:
    """Subtract two numbers.
    
    Args:
        a: first float
        b: second float

    Returns:
        Result float
    """
    return a - b
    
def multiply(a: float, b: float) -> float:
    """Multiply two numbers.
    Args:
        a: first float
        b: second float

    Returns:
        Result float
    """
    return a * b

def divide(a: float, b: float) -> float:
    """Divide two numbers.
    
    Args:
        a: first float
        b: second float

    Returns:
        Result float
    """
    if b == 0:
        raise ValueError("Cannot divide by zero.")
    return a / b

def modulus(a: float, b: float) -> float:
    """Get the modulus of two numbers.
    
    Args:
        a: first float
        b: second float

    Returns:
        Result float
    """
    return a % b