Errors and Experimentation

Get Started with Python - Part 4

This is the fourth part of the Jump In guide. Here, we focus on errors and experimentation. Errors are a normal part of learning and programming. Consider them hints that something needs adjusting, not failures. Experimentation is about testing your ideas safely with small, simple steps.

Common Errors

Python errors usually come with a message that describes what went wrong. Below are the most common types beginners see:

SyntaxError

A SyntaxError happens when Python doesn’t understand the code structure (missing a parenthesis, colon, etc.).

NameError

A NameError occurs when you try to use something that hasn’t been defined yet.

TypeError and ValueError

TypeError means the wrong type of object was used. ValueError means the type was right but the value didn’t make sense.

IndexError

IndexError means you asked for a position that doesn’t exist.

File Errors

FileNotFoundError and PermissionError happen when files or paths don’t exist or can’t be accessed. Relative vs. absolute paths, and read/write permissions, can all matter here.

Big Picture Errors

Sometimes errors come from bigger issues: the Python version you’re using, missing packages, or environment setup. This browser based tutorial should avoid any of those for now.

But be aware, those errors can cause lots of headaches.

Debugging is most effective when structured, check out On the Shoulders of Giants for more general tips.

Experimentation

Experimentation means testing your ideas step by step. Debugging works a lot like science. Instead of guessing randomly, you can treat each step as a test:

• Form a hypothesis: “Maybe the list is empty.”

• Test it: print(len(my_list))

• Observe: Check if the result matches your idea.

• Revise: If not, try a new explanation.

Issue	Wild Guess	Testable Hypothesis	Test Syntax/Process
Can’t load a file	I deleted it	The file still exists, just in the wrong place	Check Finder/Explorer, confirm relative vs. absolute path
I can’t remember all this syntax	I cannot code	Other learners look things up too	Search docs, Stack Overflow, or examples — even experts do this
I keep getting errors	This will never run, I should give up	Repeated errors show where my understanding is growing	Review progress, look for recurring issues, adjust and retry
Loop runs forever	Python is broken	My loop condition never becomes false	Print the variable in the loop, check where/if it changes
Unexpected output	Computer is wrong	The variable has a different type or value than I expect	Use type(x), print(x), or len(x) to inspect
Function gives error	Functions are too advanced for me	I passed the wrong number/type of arguments	Check the function definition and call, print the inputs

Check Types and Values

Print Often

Use len() to Check Size

Comment and Change Slowly

Use # to comment out lines temporarily. Make one change at a time and re-run to see the effect.

Use f-Strings for Context Printing

Instead of guessing what a printed value means, f-strings let you add context directly in the output. They are one of the easiest ways to add clarity to print statements and much more.

• Errors are hints, not failures.
• Experiment with simple tools (type(), print(), len()).
• More advanced error topics like environments, packages, and permissions are covered elsewhere.