Slicing

What you are building

The task in front of you: What does [0:2] return?.

The editor already holds a working starting point. Do not delete it and start again — read it, change one thing, run it, and watch which check moves. That loop is the whole method.

Why this matters

You are inside the section “Data structures” of the Python Programming track. Everything in this section builds towards the section project, and this task is one of the pieces that project leans on.

In real work nobody marks your code — it either runs or it does not, and someone is waiting for the result. The checks here are deliberately strict about output, because a program that prints the right thing in the wrong shape fails in the real world too.

The key idea

Python reads a line, runs it, and remembers the names you created. That is all a script is: a list of instructions and the memory they leave behind.

Spacing is not decoration in Python — the indentation is the structure. Four spaces inside an if or a def is what tells the interpreter those lines belong together.

Two mistakes to avoid

• Printing your value outside the loop instead of inside it, or inside when it should be after — count how many lines the answer should have before you run.
• Mixing tabs and spaces. It looks identical on screen and Python will refuse to run the file.

What the automatic checks look for

The right-hand column runs 1 check every time you press Run code. Nothing is hidden:

• The output has to contain “out:[10, 20]”.