#!/usr/bin/env python3
# -*- coding: utf-8 -*-


#
# Task 1
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print("Introduction to Python programming")


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# Task 2
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# TODO: Create a list with values 1--20.
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# ???
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# TODO: Use a list comprehension to square all odd values in this list (keep even values unchanged).
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# ???
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# TODO: Request a number from the user (terminal keyboard input), loop this to get 4 numbers, and sort the numbers in ascending order.
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# ???
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# Task 3
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# Write a function that ...
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# TODO: ... squares all elements of a list.
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# ???
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# TODO: ... recursively calculates the sum of all elements in a list.
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# ???
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# TODO: ... uses the built-in Python function `sum(list)` to calculate the arithmetic mean of all elements in a list.
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# ???
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# Task 4
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import math

# Write a class `Vec2` that has ...
# TODO: ... a variable `id`, and a "global" class variable `gid` that is used to assign each instance a unique `id`.
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# ???
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    # TODO: ... a constructor that initializes two variables `x` and `y`.
    #
    # ???
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    # TODO: ... a member function `length(self)` that calculates and returns the euclidean length of the vector.
    #
    # ???
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    # TODO: ... a member function `add(self, rhs)` that calculates the component-wise sum of the vector and another one (`rhs`).
    #
    # ???
    #

# TODO: Vec2 demo
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# ???
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