You are working on a custom Web application to create a document library for a client. The main function of the document library is allowing the user to locate documents based on keywords within the document. Because of licensing considerations, the client does not want to use a commercial search engine, so you need to develop one from scratch.
1. You need to write a program to find keywords in a document.
2. You must also rank the document's relevance by the number of times the input keyword occurs in the document.