It's just that simple! When you don't except "NO", 1 of 2 things things happen.
Here is an example. Yesterday, I needed to figure out why my clothes washer was not taking in hot water. Since, I can get behind my washer without to much effort, I had a YouTube video telling my DIY self to start by checking the hot water inlet. I went to turn off the hot water supply from behind the washer. As I turned the knob, it fall off it my hand. It was missing the nut. So not knowing the size of the nut, I put my phone under the stem and took a picture of the complete cold water side. With knob, washer and phone with photo, I headed to my local Ace Hardware. I love Ace because they usually have very helpful staff and 2 walls of nuts, bolts, washers and stuff I can't even explain and the best part is, I can buy just the quantity I need.