old_contents: class Particle:
      '''
      A class representing a particle
      '''
  
      def __init__(self):
          self.energy = energy
          self.positon = position
          self.particle_id = particle
          self.parent_id = parent_id
  
new_contents: class Particle:
      """
      A class representing a particle
      """
  
      def __init__(self,
                  energy,
                  position,
                  rad_length,
                  term_dist,
                  parent=None,
                  results=None):
          self.energy = energy
          self.position = position
          self.rad_length = rad_length
          self.term_distance = term_dist
          self.parent = parent
          self.results = results
          self.child_1 = None
          self.child_2 = None
  
subject: Add base particle class