code: def retrieve(self, value):  # type: (Any) -> Any
          
          if isinstance(value, string_types):
              for key, this_value in self.secrets.items():
                  value = value.replace(key, this_value)
          elif isinstance(value, MutableMapping):
              return {k: self.retrieve(v) for k, v in value.items()}
          elif isinstance(value, MutableSequence):
              return [self.retrieve(v) for k, v in enumerate(value)]
          return value
docs: Replace placeholders with their corresponding secrets.