code: def sub(self, *segments):
          "Get a sub-configuration."
          d = self
          for segment in segments:
              try:
                  d = d[segment]
              except KeyError:
                  return ConfigDict({})
          return f sub(self, *segments):
          "Get a sub-configuration."
          d = self
          for segment in segments:
              try:
                  d = d[segment]
              except KeyError:
                  return ConfigDict({})
          return d
docs: Get a sub-configuration.