code: public String getString(String key) {
  	    Object obj = get(key);
  	    if (obj != null && obj instanceof String) {
  		    return (String) obj;
  	        
  		}
  	    return null;
  	    
  	}
docs: Get the first item in KB matching the key as a String.
  @param key the key for the knowledge base entry
  @return the entry, or {@code null} if not a {@code String} or does not exist