catchup_screen.py

class Screen:
    def __init__(self, size):
        self.size = size
        # create an array with `size` lines of `size` dots
        # multiplying a string like `"hello world! " * 20`
        # then multiplying the array
        self.screen = ['.' * size] * size

    def __str__(self):
        return str.join("\n", self.screen)

    def present(self):
        for line in self.screen:
            for char in line:
                # normally `print` ends with a new line, we
                # set it to empty so we can print many dots
                # on the same line.
                print(char, end="")
            print()
    
    def clear(self):
        # same as __init__
        self.screen = ['.' * self.size] * self.size
    
    def draw(self, position, char):
        # python does not allow modifying strings, but we can
        # convert them into a list/array and then combine
        # the list back into a string. Ugly, i know.
        ct = list(self.screen[position.y])
        ct[position.x] = char
        self.screen[position.y] = str.join("", ct)


class Point:
    def __init__(self, x, y):
        self.x = x
        self.y = y

screen = Screen(20)
screen.draw(Point(19, 15), "@")
screen.present()