text: import numpy as np
  import random as rand
  from rvv_functions import *
  from rvv_pushers import *
  
  B = np.array([rand.random(),rand.random(),rand.random()])
  E = np.array([rand.random(),rand.random(),rand.random()])
  x  = np.array([rand.random(),rand.random(),rand.random()])
  u_old  = np.array([rand.random(),rand.random(),rand.random()]) - 0.1
  c = 1
  dt = 0.5
  
  u_new = boris(x,u_old,E,B,dt)
  defect = u_new - u_old - (E+np.cross((u_old+u_new)/2,B))*dt
  print(defect)
  