code: def update(self, enabled=None, cnames=None, comment=None):
          
          new_config = StreamingDistributionConfig(self.connection,
                                                   self.config.origin,
                                                   self.config.enabled,
                                                   self.config.caller_reference,
                                                   self.config.cnames,
                                                   self.config.comment,
                                                   self.config.trusted_signers)
          if enabled != None:
              new_config.enabled = enabled
          if cnames != None:
              new_config.cnames = cnames
          if comment != None:
              new_config.comment = comment
          self.etag = self.connection.set_streaming_distribution_config(self.id,
                                                                        self.etag,
                                                                        new_config)
          self.config = new_config
          self._object_class = StreamingObject
docs: Update the configuration of the StreamingDistribution.  The only values
          of the StreamingDistributionConfig that can be directly updated are:
  
           * CNAMES
           * Comment
           * Whether the Distribution is enabled or not
  
          Any changes to the ``trusted_signers`` or ``origin`` properties of
          this distribution's current config object will also be included in
          the update. Therefore, to set the origin access identity for this
          distribution, set
          ``StreamingDistribution.config.origin.origin_access_identity``
          before calling this update method.
  
          :type enabled: bool
          :param enabled: Whether the StreamingDistribution is active or not.
  
          :type cnames: list of str
          :param cnames: The DNS CNAME's associated with this
                          Distribution.  Maximum of 10 values.
  
          :type comment: str or unicode
          :param comment: The comment associated with the Distribution.