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: First the frog lays the eggs, then the warmth from the sun makes the eggs hatch into baby tadpoles. 
Sentence2: sun keeps eggs warm.

sun