Modify for recognizing specific word

Hello, Your api is very useful. But I want to add a few more features, can you help?
1. I want to print only when a specific word is recognized. For example, when the user says "red blue apple", I want to output the resulting text only when "blue" is included.
ex) speak : red
result : (nothing)
speak : blue
result : blue
speak: red blue apple
result: blue
I am currently using test_microphone.py of the python example, and looking inside the code, the part that outputs the result seems to be the print(rec.Result()) part. Could you please tell me how to fix it?