This will probably be a little series :)
X-Shape
You will get an odd Integer n (>= 3) and your task is to draw a X. Each line is separated with '\n'.
Use the following characters:  ■ □
For Ruby, Crystal and PHP:   whitespace and o 
e.g.:
                                     ■□□□■
            ■□■                      □■□■□
  x(3) =>   □■□              x(5)=>  □□■□□
            ■□■                      □■□■□
                                     ■□□□■
 Series: ASCII Fun
ASCII Fun #1: X-Shape
ASCII Fun #2: Funny Dots
ASCII Fun #3: Puzzle Tiles
ASCII Fun #4: Build a pyramid
f, e = "■□"


def x(n):
    l = n // 2
    middle = [f"{e * l}{f}{e * l}"]
    half = [f"{e * i}{f}{e * (n - 2*i - 2)}{f}{e * i}" for i in range(l)]
    return "\n".join(half + middle + half[::-1])

f, e = "■□"


def x(n):
    l = n // 2
    middle = [f"{e * l}{f}{e * l}"]
    half = [f"{e * i}{f}{e * (n - 2*i - 2)}{f}{e * i}" for i in range(l)]
    return "\n".join(half + middle + half[::-1])
