code: def process_quantity(self, properties):
          
          quant = Q_(properties[0])
          if len(properties) > 1:
              unc = properties[1]
              uncertainty = unc.get('uncertainty', False)
              upper_uncertainty = unc.get('upper-uncertainty', False)
              lower_uncertainty = unc.get('lower-uncertainty', False)
              uncertainty_type = unc.get('uncertainty-type')
              if uncertainty_type == 'relative':
                  if uncertainty:
                      quant = quant.plus_minus(float(uncertainty), relative=True)
                  elif upper_uncertainty and lower_uncertainty:
                      warn('Asymmetric uncertainties are not supported. The '
                           'maximum of lower-uncertainty and upper-uncertainty '
                           'has been used as the symmetric uncertainty.')
                      uncertainty = max(float(upper_uncertainty), float(lower_uncertainty))
                      quant = quant.plus_minus(uncertainty, relative=True)
                  else:
                      raise ValueError('Either "uncertainty" or "upper-uncertainty" and '
                                       '"lower-uncertainty" need to be specified.')
              elif uncertainty_type == 'absolute':
                  if uncertainty:
                      uncertainty = Q_(uncertainty)
                      quant = quant.plus_minus(uncertainty.to(quant.units).magnitude)
                  elif upper_uncertainty and lower_uncertainty:
                      warn('Asymmetric uncertainties are not supported. The '
                           'maximum of lower-uncertainty and upper-uncertainty '
                           'has been used as the symmetric uncertainty.')
                      uncertainty = max(Q_(upper_uncertainty), Q_(lower_uncertainty))
                      quant = quant.plus_minus(uncertainty.to(quant.units).magnitude)
                  else:
                      raise ValueError('Either "uncertainty" or "upper-uncertainty" and '
                                       '"lower-uncertainty" need to be specified.')
              else:
                  raise ValueError('uncertainty-type must be one of "absolute" or "relative"')
  
          return quant
docs: Process the uncertainty information from a given quantity and return it