class_docstr: list of beams at specific time-step
docstr: add or merge new beam into list
docstr_tok: ["add","or","merge","new","beam","into","list"]
code: def addBeam(self, beam):
      "add or merge new beam into list"
      # add if text not yet known
      if beam.getText() not in self.beams:
          self.beams[beam.getText()] = beam
      # otherwise merge with existing beam
      else:
          self.beams[beam.getText()].mergeBeam(beam)
  
imports: from __future__ import division
  from __future__ import print_function
  import copy
label_desc: Use image node_id 2 for calling the BeamList obj's underlying member method code with example usage: obj.addBeam(beam) without return types