Print Equilateral Diamonds

def diamond(height):
    if height % 2 == 0:
        raise ValueError('height must be odd')
    half_height = height / 2
    for row in xrange(height):
        if row <= half_height:
            indent = half_height - row
        else:
            indent = row - half_height
        if row <= half_height:
            fill = 0 if row == 0 else row - 2 - 1
        else:
            fill = 0 if row == height - 1 else (height - 1 - row) - 2 - 1
        left = '%sX' % (' ' - indent)
        right = '%sX' % (' ' - fill) if fill else ''
        print left + right