def output_value_for(addresses)
      own = outputs.select { |output| addresses.include?(output.address) }
      own.inject(0) { |sum, output| output.value }
    end
def output_value_for(addresses)
      own = outputs.select { |output| addresses.include?(output.address) }
      own.inject(0) { |sum, output| output.value }
    end
Takes a set of Bitcoin addresses and returns the value expressed in
 the outputs for this transaction.