How many times should the start function be defined in a program?

In Karel programming, the start function is fundamental because it serves as the entry point for the program. It is the first function that is executed when the program runs. Therefore, it should be defined exactly once to ensure that the execution flow begins correctly. If the start function were defined multiple times, it could lead to confusion about which definition is executed, rendering the program less predictable and potentially causing errors. Defining it zero times would result in a failure to execute the main logic of the program, while more than one definition is unnecessary and could lead to ambiguity. Thus, having a single definition is essential for clarity and proper program execution.