old_contents: """Computes the least-squares optimal Keplerian elements for a sequence of
     cartesian position observations.
  """
  
  import numpy as np
  import matplotlib.pyplot as plt
  
new_contents: """Computes the least-squares optimal Keplerian elements for a sequence of
     cartesian position observations.
  """
  
  import numpy as np
  import matplotlib.pyplot as plt
  
  # convention:
  # a: semi-major axis
  # e: eccentricity
  # eps: mean longitude at epoch
  # Euler angles:
  # I: inclination
  # Omega: longitude of ascending node
  # omega: argument of pericenter
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