import copy


def deep_move_rectangle(rect, dx, dy):
    """Modifies the Rectangle by moving its corner.
    Returns a new, deep copy of the rect.

    rect: Rectangle object.
    dx: How many units to shift the corner (right is positive)
    dy: How many units to shift the corner (up is positive)
    """
    rect2 = copy.deepcopy(rect)
    rect2.corner.x += dx
    rect2.corner.y += dy
    return rect2