def find_box_extrema(boxes):
"""Returns a BoxLine with the extreme values of the boxes."""
left = min(b.left for b in boxes)
right = max(b.right for b in boxes)
bottom = min(b.bottom for b in boxes)
top = max(b.top for b in boxes)
page = max(b.page for b in boxes)
return BoxLine('', left, top, right, bottom, page)
def padded_box(box, pad_width, pad_height):
"""Adds some additional margin around the box."""
return BoxLine(box.letter, box.left - pad_width, box.top + pad_height,
box.right + pad_width, box.bottom - pad_height, box.page)
