Definition: Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.
Input: Sentence1: Cats are Mammals that Shed Dogs are Mammals that Wag their tails. 
Sentence2: Playing is one way cats learn how to behave.

Cats