def num_of_blank_squares(step):
    '''Returns the number of blank squares in a square grid filled in by
    circles in a cross pattern.
    Example:
    [0][][][0]
    [][0][0][]
    [][0][0][]
    [0][][][0]
    or:
    [0][][][][0]
    [][0][][0][]
    [][][0][][]
    [][0][][0][]
    [0][][][][0]
    '''
    # if the side length is even, half the side will be a whole integer
    if step%1 == 0:
        num_of_circles = step*4
        area = (step*2)**2
        return area-num_of_circles

    # The side length can also be odd, meaning half the side will be a 
    # decimal ending in .5
    elif step%0.5 == 0:
        num_of_circles = ((step-0.5)*4)+1
        area = (step*2)**2
        return int(area - num_of_circles)

    # Raises ValueError if 'step' is not a valid input
    else:        
        raise ValueError('''parameter should be half of a whole number side of 
            a square''')
10c9aeaefed49460fd93ab9ebed2661c47ef90a0
<mask token>

def num_of_blank_squares(step):
    """Returns the number of blank squares in a square grid filled in by
    circles in a cross pattern.
    Example:
    [0][][][0]
    [][0][0][]
    [][0][0][]
    [0][][][0]
    or:
    [0][][][][0]
    [][0][][0][]
    [][][0][][]
    [][0][][0][]
    [0][][][][0]
    """
    if step % 1 == 0:
        num_of_circles = step * 4
        area = (step * 2) ** 2
        return area - num_of_circles
    elif step % 0.5 == 0:
        num_of_circles = (step - 0.5) * 4 + 1
        area = (step * 2) ** 2
        return int(area - num_of_circles)
    else:
        raise ValueError(
            """parameter should be half of a whole number side of 
            a square"""
            )

def num_of_blank_squares(step):
    '''Returns the number of blank squares in a square grid filled in by
    circles in a cross pattern.
    Example:
    [0][][][0]
    [][0][0][]
    [][0][0][]
    [0][][][0]
    or:
    [0][][][][0]
    [][0][][0][]
    [][][0][][]
    [][0][][0][]
    [0][][][][0]
    '''
    # if the side length is even, half the side will be a whole integer
    if step%1 == 0:
        num_of_circles = step*4
        area = (step*2)**2
        return area-num_of_circles

    # The side length can also be odd, meaning half the side will be a 
    # decimal ending in .5
    elif step%0.5 == 0:
        num_of_circles = ((step-0.5)*4)+1
        area = (step*2)**2
        return int(area - num_of_circles)

    # Raises ValueError if 'step' is not a valid input
    else:        
        raise ValueError('''parameter should be half of a whole number side of 
            a square''')