def index_of_square(square):
    """
    Index of square

    Args:
        square (String): Square in chess notation e.g. f7

    Returns:
        Int: Index of square in bitboard
    """
    line = ord(square[0].lower()) - ord('a')
    row = int(square[1])
    idx = 8 * (row - 1) + line
    return idx