Mutating a Dictionary: Add, Overwrite, del, and in

Why does one assignment both add an entry and silently overwrite one — and why is 'B' in grades False when B is sitting right there?

Finger exercises

Short drills on what this video just taught. Write the code, run the checks, and reveal the answer only if you are stuck.

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Exercise 1 of 5

One syntax, two different outcomes

Here is a small price list:

prices = {'apple': 3, 'banana': 2, 'cherry': 7}

Two things have changed at the market: a date is now sold, at a price of 5, and a banana now costs 4 instead of 2. Apply both changes to prices itself — one statement each, using the same square-bracket assignment both times.

prices = {'apple': 3, 'banana': 2, 'cherry': 7}

# your code here — one statement per change

prices = {'apple': 3, 'banana': 2, 'cherry': 7}

# your code here — one statement per change

Python runs in your browser

⌘/Ctrl + Enter runs

the new item is on the price list

the banana price was overwritten, not duplicated

apple and cherry are untouched

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