References: https://arxiv.org/pdf/1912.05911 https://arxiv.org/pdf/1808.03314 https://stanford.edu/~shervine/teaching/cs-230/cheatsheet-recurrent-neural-networks https://www.d2l.ai/chapter_recurrent-neural-networks https://www.geeksforgeeks.org/machine-learning/introduction-to-recurrent-neural-network