Zero-Touch Provisioning (ZTP) is a highly scalable Day 0 provisioning method that allows network devices to automatically configure themselves without manual intervention. It is ideal for large-scale deployments where devices can boot, obtain a configuration, and join the network automatically.

The script calls set_interfaces() but does not store its return value. Therefore, the variable interfaces used in the for loop is undefined, causing a NameError. Assigning the return value to interfaces like this:
interfaces = set_interfaces()
inside the main() function will resolve the error and allow the script to execute successfully.

https://www.cisco.com/c/en/us/td/docs/ios-
xml/ios/prog/configuration/166/b_166_programmability_cg/restconf_prog_int.pdf