import math


def angle(corners):
    """Returns the angular skew of the tree, 0 is perfectly vertical"""
    left_x, left_y = corners.bottom_left
    right_x, right_y = corners.bottom_right
    top_x, top_y = corners.top

    theo_x = (right_x - left_x) / 2 + left_x
    offset = abs(theo_x - top_x)
    height = round(abs(left_y + right_x) / 2) - top_y
    return math.degrees(math.atan(offset / height))