Given a list of white pawns on a chessboard (any number of them, meaning from 0 to 64 and with the possibility to be positioned everywhere), determine how many of them have their backs covered by another. 
Pawns attacking upwards since we have only white ones.
Please remember that a pawn attack(and defend as well) only the 2 square on the sides in front of him. https://en.wikipedia.org/wiki/Pawn_(chess)#/media/File:Pawn_(chess)_movements.gif
This is how the chess board coordinates are defined:
ABCDEFGH8♜♞♝♛♚♝♞♜7♟♟♟♟♟♟♟♟65432♙♙♙♙♙♙♙♙1♖♘♗♕♔♗♘♖
def covered_pawns(pawns):
    count = 0
    for i in range(len(pawns)):
        x, y = list(pawns[i])
        if "".join([chr(ord(x) - 1), str(int(y) - 1)]) in pawns or \
                "".join([chr(ord(x) + 1), str(int(y) - 1)]) in pawns:
            count += 1
    return count
def covered_pawns(pawns):
    count = 0
    for i in range(len(pawns)):
        x, y = list(pawns[i])
        if "".join([chr(ord(x) - 1), str(int(y) - 1)]) in pawns or \
                "".join([chr(ord(x) + 1), str(int(y) - 1)]) in pawns:
            count += 1
    return count