def inventory_report(products):
    """
    Takes a list of Acme products and prints a summary

    Summary will incldue:

        * Number of unique product names
        * Average price
        * Average weight
        * Average flammability
    """
    def most_common(lst):
        """
        Returns most common item in a list
        """
        return max(set(lst), key=lst.count)
    count = float(len(products))
    unique = len(set([prod.name for prod in products]))
    avg_price = sum([prod.price for prod in products]) / count
    avg_weight = sum([prod.weight for prod in products]) / count
    avg_flammability = sum([prod.flammability for prod in products]) / count

    print ('Number of Unique Product Names: %d' % unique)
    print ('Most Popular Product: %s' %
           most_common([prod.name for prod in products]))
    print ('Average Price: %.2f' % avg_price)
    print ('Average Weight: %.2f' % avg_weight)
    print ('Average Flammability: %.2f' % avg_flammability)