Implement a simple expert system using the forward chaining inference method to diagnose medical conditions based on symptoms. The expert system should consist of a knowledge base containing rules and facts about medical conditions and symptoms. The system should be able to infer the possible medical conditions given a set of symptoms provided by the user. Requirements: 1. Define a set of medical conditions, symptoms, and rules in the knowledge base. 2. Implement the forward chaining inference method to infer medical conditions based on symptoms. 3. Allow users to input their symptoms and display the possible medical conditions.

Implement a simple expert system using the forward chaining inference method to diagnose medical conditions based on symptoms. The expert system should consist of a knowledge base containing rules and facts about medical conditions and symptoms. The system should be able to infer the possible medical conditions given a set of symptoms provided by the user. Requirements: 1. Define a set of medical conditions, symptoms, and rules in the knowledge base. 2. Implement the forward chaining inference method to infer medical conditions based on symptoms. 3. Allow users to input their symptoms and display the possible medical conditions.