Working with Python collections—lists, tuples, and dictionaries—is fundamental for any developer. However, one common source of confusion, especially for those new to Python, is remembering which brackets or symbols are used for each type.

This blog post outlines a simple and effective technique to avoid this confusion and write cleaner, more accurate code.

The Problem

Python provides three primary built-in collection types:

1. list — an ordered, mutable sequence
2. tuple — an ordered, immutable sequence
3. dict — a collection of key-value pairs

Each of these uses a different symbol:

1. [] for lists
2. () for tuples
3. {} for dictionaries

Despite the differences, it's easy to mistakenly swap these brackets, especially when moving quickly or switching between languages.

A Simple Trick: Use the Third Character

To eliminate this confusion, a helpful memory technique is to focus on the third character in the name of the collection:

This subtle pattern can serve as a quick mental reference, particularly when context-switching or reviewing code.

Practical Example

Using the third character technique, you can more easily recall:

1. "S" for Square brackets → List
2. "P" for Parentheses → Tuple
3. "C" for Curly braces → Dict

What about Set

set also uses curly braces {}, it's often confused with dict. but as dict always have key-value pairs but set always have single unique values

If it's {} with key-value, it's a dict

If it's {} with only values, it's a set

Conclusion

Being precise with syntax is crucial when working with any programming language. Small errors—like using the wrong brackets—can lead to bugs or unintended behavior. Leveraging memory techniques like this one helps reduce errors and reinforces long-term understanding.

For professionals aiming to write robust and readable Python code, clarity in syntax is as important as the logic itself.