code: def addUsage_Label(self,usage_label):
          '''Appends one Usage_Label to usage_labels
          '''
          if isinstance(usage_label, Usage_Label):
              self.usage_labels.append(usage_label)
          else:
              raise (Usage_LabelError,
                     'usage_label Type should be Usage_Label, not %s' % type(
                      usage_label)
                     f addUsage_Label(self,usage_label):
          '''Appends one Usage_Label to usage_labels
          '''
          if isinstance(usage_label, Usage_Label):
              self.usage_labels.append(usage_label)
          else:
              raise (Usage_LabelError,
                     'usage_label Type should be Usage_Label, not %s' % type(
                      usage_label)
                     )
docs: Appends one Usage_Label to usage_labels