text: # This file is part of comma, a generic and flexible library
  # Copyright (c) 2011 The University of Sydney
  # All rights reserved.
  #
  # Redistribution and use in source and binary forms, with or without
  # modification, are permitted provided that the following conditions are met:
  # 1. Redistributions of source code must retain the above copyright
  #    notice, this list of conditions and the following disclaimer.
  # 2. Redistributions in binary form must reproduce the above copyright
  #    notice, this list of conditions and the following disclaimer in the
  #    documentation and/or other materials provided with the distribution.
  # 3. Neither the name of the University of Sydney nor the
  #    names of its contributors may be used to endorse or promote products
  #    derived from this software without specific prior written permission.
  #
  # NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE
  # GRANTED BY THIS LICENSE.  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT
  # HOLDERS AND CONTRIBUTORS \"AS IS\" AND ANY EXPRESS OR IMPLIED
  # WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  # MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  # DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  # LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  # CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  # SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  # BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  # WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
  # OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
  # IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  from __future__ import absolute_import
  from __future__ import print_function
  import signal
  import sys
  import os
  
  MANAGED_SIGNALS = ( signal.SIGINT, signal.SIGTERM, signal.SIGHUP )
  
  class is_shutdown(object):
      def __init__( self, verbose = False ):
          self.state = False
          self.verbose = verbose
          for s in MANAGED_SIGNALS: signal.signal( s, self.switch_on )
  
      def switch_on( self, signum, frame ):
          self.state = True
          if self.verbose: print( os.path.basename( sys.argv[0] ), ": caught signal:", signum, file = sys.stderr )
  
      def __bool__( self ): return self.state
  
      __nonzero__ = __bool__
  
  # signal.signal( signal.SIGPIPE, signal.SIG_DFL )
  