What is this wire?

"Some repair shops advocate bypassing the thermal fuse by adding a jumper wire. While this method does determine whether the fuse is bad, it is too easy to forget to remove the jumper and replace the thermal fuse. Instead, remove the wire leads from the thermal fuse and set a multitester to its lowest RX setting. Touch the tester’s probes to each terminal on the fuse. A reading of infinity indicates the thermal fuse is good. Any other reading means the fuse has triggered and must be replaced."