Write a program that asks the user for the name of the file. The program should write the contents of this input file to an output file. In the output file, each line should be preceded with a line number followed by a colon. The output file will have the same name as the input filename, preceded by "ln" (for line numbers). Be sure to use try/except to catch all exceptions.

Python Read And Write File: With Examples • Python Land Tutorial

Python Read and Write Files