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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def angle_between(u_vec, v_vec):
 """Given 2 vectors in `v` and `u`, return the angle separating them. This works whether `v` and `u` each have the shape ``(3,)``, or whether they are each whole arrays of corresponding x, y, and z coordinates and have shape ``(3, N)``. The returned angle will be between 0 and 180 degrees. This formula is from Section 12 of: https://people.eecs.berkeley.edu/~wkahan/Mindless.pdf """

    u = length_of(u_vec)
    v = length_of(v_vec)
    num = v*u_vec - u*v_vec
    denom = v*u_vec + u*v_vec
    return 2*arctan2(length_of(num), length_of(denom))