code: def addition_rule(self, units):
      for unit_1, unit_2 in zip(units[:-1], units[1:]):
          if unit_1 != unit_2:
              return NotImplemented
      return units[0]
  
imports: import math
  from packaging.version import parse
  import numpy
  import matplotlib.ticker
  import matplotlib.units
label_desc: Use image node_id 1 for calling the UnitResolver obj's underlying member method code with example usage: obj.addition_rule(units) and returns: units, NotImplemented