text: # The MIT License (MIT) # Copyright (c) 2014-2017 University of Bristol
  #
  #  Permission is hereby granted, free of charge, to any person obtaining a copy
  #  of this software and associated documentation files (the "Software"), to deal
  #  in the Software without restriction, including without limitation the rights
  #  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  #  copies of the Software, and to permit persons to whom the Software is
  #  furnished to do so, subject to the following conditions:
  #
  #  The above copyright notice and this permission notice shall be included in all
  #  copies or substantial portions of the Software.
  #
  #  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  #  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  #  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  #  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  #  DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  #  OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
  #  OR OTHER DEALINGS IN THE SOFTWARE.
  
  from hyperstream.tool import Tool, check_input_stream_count
  from hyperstream.stream import StreamInstance
  
  
  class Product(Tool):
      @check_input_stream_count(2)
      def _execute(self, sources, alignment_stream, interval):
          s0 = sources[0].window(interval, force_calculation=True)
          s1 = sources[1].window(interval, force_calculation=True)
  
          for (d0, d1) in zip(s0, s1):
              if d0.timestamp != d1.timestamp:
                  raise ValueError("{} tool expects aligned timestamps".format(self.name))
              yield StreamInstance(d0.timestamp, d0.value * d1.value)
  