new_contents: ##
  # Copyright (c) 2009 Apple Inc. All rights reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  # http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  ##
  
  """
  Extensions to twisted.python.log.
  """
  
  from sys import stdout, stderr
  
  from twisted.python.log import addObserver
  
  class StandardIOObserver (object):
      """
      Log observer that writes to standard I/O.
      """
      def emit(self, eventDict):
          text = None
  
          if eventDict["isError"]:
              output = stderr
              if "failure" in eventDict:
                  text = eventDict["failure"].getTraceback()
          else:
              output = stdout
  
          if not text:
              text = " ".join([str(m) for m in eventDict["message"]]) + "\n"
  
          output.write(text)
          output.flush()
  
      def start(self):
          addObserver(self.emit)
  
      def stop(self):
          removeObserver(self.emit)
  
subject: Add StandardIOObserver