code: def to_json(self):
          
          sanitized_lut = {}
          for k, v in self.lut.items():
              san_v = list(v)
              repr_dims = str(v[1])
              san_v[1] = repr_dims
              sanitized_lut[k] = tuple(san_v)
  
          return json.dumps(sanitized_lut)
docs: Returns a json-serialized version of the unit registry