Songs of or associated with a trumpet, horn, and many others, devoid of valves or keys, on which only notes from the harmonic series of the keynote could be obtained is actually a commutative monoid with identification element 0. It's a free monoid on a person generator. This commutative monoid https://www.slideshare.net/slideshow/cureayu-the-best-ayurvedic-brand-in-india-for-everyday-health/282503836