def subtract(x, y):
    """
    Subtracts y from x and returns the difference
    :param x: (int)
    :param y: (int)
    :return: (int) x-y
    """
    return x - y


def add(x, y):
    """
    Adds x to y and returns the sum
    :param x: (int)
    :param y: (int)
    :return: (int) x+y
    """
    return x + y


def multiply(x, y):
    """
    Multiplies x to y and returns the product
    :param x: (int)
    :param y: (int)
    :return: (int) x*y
    """
    return x * y


def exponent(x, y):
    """
    Raises x to the power of y and returns it
    :param x: (int)
    :param y: (int)
    :return: (int) x^y
    """
    return x ** y


def add2(values):
    """
    Receives a tuple of two numbers and returns their sum
    :param values: (tuple of numbers)
    :return: (int) values[0] + values[1]
    """
    (x, y) = values
    return x + y


def double(x):
    """
    Doubles x and returns it
    :param x: (int)
    :return: (int) 2*x
    """
    return 2 * x


def is_even(num):
    """
    Returns whether num is an even number
    :param num: (int)
    :return: (bool) whether num is an even number
    """
    return num % 2 == 0


def apply_function(some_function, x, y):
    """
    Calls some_function passing to it x and y as arguments and returns the result
    :param some_function: (function) a function that takes two parameters
    :param x: (Any)
    :param y: (Any)
    :return: (Any)
    """
    return some_function(x, y)


def apply_function_to_list(f, some_list):
    """
    Calls f on each item of some_list and returns the results in a list
    :param f: (function) a function that takes one parameter
    :param some_list: (list)
    :return: (list)
    """
    result = []

    for val in some_list:
        result.append(f(val))

    return result


def apply_function_to_tuple(f, some_list):
    """
    Calls f on each tuple of some_list and returns the results in a list
    :param f: (function) a function that takes two parameters
    :param some_list: (list) a list of 2-tuples
    :return: (list)
    """
    result = []

    for (x, y) in some_list:
        result.append(f(x, y))

    return result


def filter_list(some_function, some_list):
    """
    Returns a list of all elements of some_list that would return True when passed to some_function
    :param some_function: (function) a function that takes one parameter and returns a bool
    :param some_list: (list)
    :return: (list)
    """
    result = []

    for val in some_list:
        if some_function(val):
            result.append(val)

    return result


def kinda_crazy(num):
    def multiplier(x):
        return num * x
    return multiplier


def crazy(num):
    return lambda x: num * x