code: def angle(v1, v2):
      """find the angle between two 3D vectors.
  
      Parameters
      ----------
      v1 : list, first vector
      v2 : list, second vector
  
      Returns
      -------
      angle : float, the angle
      """
      return np.arccos(
          np.dot(v1, v2) / (np.linalg.norm(v1) * np.linalg.norm(v2))
      )
  
imports: from __future__ import division
  from __future__ import print_function
  import multiprocessing
  from itertools import combinations
  from multiprocessing import Pool
  import numba
  import numpy
  from sklearn.preprocessing import MinMaxScaler, RobustScaler
  from sklearn.utils import check_array
  from .base import BaseDetector
label_desc: Use image node_id 2 for calling a global function with example usage: angle(v1, v2) and returns: np