How do you use the word whistle in a sentence as noun?

Here are a few examples of using "whistle" as a noun in a sentence:

* "The train engineer blew a long, mournful whistle as it pulled out of the station." (Here, "whistle" refers to the sound made by the train.)

* "She kept a silver whistle on her keychain for emergencies." (Here, "whistle" refers to the physical object used to make a sound.)

* "The referee blew his whistle, signaling the end of the game." (Here, "whistle" refers to the specific tool used by the referee.)

* "He learned to play a cheerful tune on his whistle." (Here, "whistle" refers to a musical instrument.)