text: # -*- coding: utf-8 -*-
  # Copyright 2014-2016 OpenMarket Ltd
  # Copyright 2018-9 New Vector Ltd
  #
  # 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.
  
  """ This is a reference implementation of a Matrix homeserver.
  """
  
  import json
  import os
  import sys
  
  # Check that we're not running on an unsupported Python version.
  if sys.version_info < (3, 5):
      print("Synapse requires Python 3.5 or above.")
      sys.exit(1)
  
  # Twisted and canonicaljson will fail to import when this file is executed to
  # get the __version__ during a fresh install. That's OK and subsequent calls to
  # actually start Synapse will import these libraries fine.
  try:
      from twisted.internet import protocol
      from twisted.internet.protocol import Factory
      from twisted.names.dns import DNSDatagramProtocol
  
      protocol.Factory.noisy = False
      Factory.noisy = False
      DNSDatagramProtocol.noisy = False
  except ImportError:
      pass
  
  # Use the standard library json implementation instead of simplejson.
  try:
      from canonicaljson import set_json_library
  
      set_json_library(json)
  except ImportError:
      pass
  
  __version__ = "1.21.0"
  
  if bool(os.environ.get("SYNAPSE_TEST_PATCH_LOG_CONTEXTS", False)):
      # We import here so that we don't have to install a bunch of deps when
      # running the packaging tox test.
      from synapse.util.patch_inline_callbacks import do_patch
  
      do_patch()
  