code: def add(self, value):  # type: (Text) -> Text
          
          if not isinstance(value, string_types):
              raise Exception("Secret store only accepts strings")
  
          if value not in self.secrets:
              placeholder = "(secret-%s)" % Text(uuid.uuid4())
              self.secrets[placeholder] = value
              return placeholder
          return value
docs: Add the given value to the store.
  
          Returns a placeholder value to use until the real value is needed.