Write a function which takes one parameter representing the dimensions of a checkered board. The board will always be square, so 5 means you will need a 5x5 board.
The dark squares will be represented by a unicode white square, while the light squares will be represented by a unicode black square (the opposite colours ensure the board doesn't look reversed on code wars' dark background). It should return a string of the board with a space in between each square and taking into account new lines. 
An even number should return a board that begins with a dark square. An odd number should return a board that begins with a light square.
The input is expected to be a whole number that's at least two, and returns false otherwise (Nothing in Haskell).
Examples:
```python
checkered_board(5)
```
returns the string
```
■ □ ■ □ ■
□ ■ □ ■ □
■ □ ■ □ ■
□ ■ □ ■ □
■ □ ■ □ ■
```
**There should be no trailing white space at the end of each line, or new line characters at the end of the string.**
**Note**   
Do not use HTML entities for the squares (e.g. `□` for white square) as the code doesn't consider it a valid square. A good way to check is if your solution prints a correct checker board on your local terminal.  
**Ruby note:**
CodeWars has encoding issues with rendered unicode in Ruby.
You'll need to use unicode source code (e.g. "\u25A0") instead of rendered unicode (e.g "■").
def checkered_board(n):
    if type(n) is not int or n <2: return False
    return '\n'.join(map(lambda i: ' '.join(map(lambda j: '□' if ((n-j) + i) % 2 == 0 else '■', range(n))), range(n)))
def checkered_board(n):
    if type(n) is not int or n <2: return False
    return '\n'.join(map(lambda i: ' '.join(map(lambda j: '□' if ((n-j) + i) % 2 == 0 else '■', range(n))), range(n)))