>>> from BVHToolkit import Animation, Pose, Bone
>>> from cgkit.bvh import Node

>>> """Load BVH and get node positions."""
>>> animation = Animation.from_bvh("path_to_bvh.bvh")
>>> pose = animation.get_pose(3)    # get pose at third frame
>>> pose.get_position(0)    # get position of the root node
(0, 0, 0)
>>> pose.get_position(10)   # get position of the 10th node
(123, 456, 789)

>>> """Do same thing in nodes generated in the code"""
>>> n0 = Node()
>>> n0.channels = ["Xposition", "Yposition"]
>>> n1 = Node()
>>> n1.offset = (10, 0, 0)
>>> n0.children.append(n1)

>>> pose = Pose(Bone(n0), [0, 0]) # create Pose from Bone, which wraps Node, and frame parameters
>>> pose.get_position(n1)
(10, 0, 0)

>>> pose = Pose(Bone(n0), [10, 10])
>>> pose.get_position(n1)
(20, 10, 0)