Add Dunder Methods as a Python TIL

python/dunder-methods.md

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+# Dunder Methods
+
+Python has all kinds of special, or rather, _magic_ methods that allow for
+customizing all kinds of class behavior. There is `__init__()`, `__bool__()`,
+and so many others.
+
+The thing they all have in common is that their names are wrapped in _double
+underscores_. This is why they are called _dunder methods_.
+
+Some of these are used every single day, like the `__init__()` method for
+defining how a class should create an object. Others, used from time to time,
+are for overriding how comparisons or conversions happen. E.g. you may want to
+override `__bool__()` or `__len__()` to customize the truthiness of a custom
+class.
+
+There are so many others, ones you probably haven't even heard of. To see a
+full listing, check out this [cheat sheet of every dunder
+method](https://www.pythonmorsels.com/every-dunder-method/#cheat-sheet).
+
+Note: these are not to be confused with _dunder attributes_ which are things
+like `__name__`, `__file__`, and `__version__` which correspond to a value that
+you can access in a specific context rather than behavior to override.