code: def write_env_vars(env_vars=None):  # type: (dict) -> None
      
      env_vars = env_vars or {}
      env_vars['PYTHONPATH'] = ':'.join(sys.path)
  
      for name, value in env_vars.items():
          os.environ[name] = value
docs: Write the dictionary env_vars in the system, as environment variables.
  
      Args:
          env_vars ():
  
      Returns: