Dict Profile.

Second Data class. A list stores a sequence. A person’s profile, though, has named fields: age, height, weight — not “first, second, third”.

A dictionary (dict) maps key → value. Keys are usually quoted strings. The syntax uses curly braces {}:

profile = {"age": 25, "height": 1.8, "weight": 75.0}

Reading uses square brackets and the key: profile["age"] → 25. This is not a list index — you ask by name. If you mistype the key (for example "Age" with a capital letter), Python looks for a different field and raises KeyError.

Mini example:

person = {"name": "Ada", "year": 1815}
print(person["name"])
print(person["year"])

Why a dict instead of three separate variables? Because the profile is one object: later you pass it to functions, add keys, serialize it. Today we only create and read.

Common mistake: writing profile["age"] as profile.age (a different style, not for this lesson); keys without quotes; mixing list and dict brackets.