Bip39 mnemonic example https://squareblogs.net/edelinepge/using-python-to-produce-a-bip39-mnemonic-a-developers-point-of-view It truly is important that the mnemonic sentences are created from randomly picked figures! These figures can be created in a number of different ways, which are explained in other articles or blog posts in this article, like "What on earth is an RNG" and Seed https://mediasocially.com/story5451288/bip39-full-list-indicators-on-bip39-ian-coleman-you-should-know-https-t-me-bip39-chat 
