Module 6
Debugging functions
Finding and fixing errors in functions.
When functions do not work
Functions can have errors just like any other code. Common problems include: forgetting to return a value, wrong indentation, or misspelling the function name.
Python
# Common mistake: forgetting return
def broken_gc(seq):
(seq.count("G") + seq.count("C")) / len(seq) * 100
result = broken_gc("ATGC")
print(result)→ None
The function computes the value but does not return it. The result is None. Always use return when you want to get a value back.
What happens if a function does not use return?