defaultdict(default_factory, **kwargs)is a subclass of Python standard dictionary (dict).

Python creators added several "versions" of standard dict implementation to answer some of the most common user problems.

If you call a non existent key in a standard, normal dict in Python you will get a KeyError. You can avoid this with get() method but if you would like to provide a default value for all keys that you will call in your dict, then defaultdict is a way to go.

To use defaultdict, you must import it from the collections module.

default_factory needs to be a callable (such as int, list, lambda, etc.) used to calculate the default value. It cannot accept arguments and must return the value to be used as the default.

Note: If defaultdict is initialized without a default_factory, it behaves like a regular dictionary and will raise a KeyError for missing keys.

partial(func, *args, **kwargs) function can be used to partially "save" elements of a function before actually calling it. We can assign a partial() function to a variable and execute it later in our code. We can "save" this function with all necessary arguments or only some of them (and provide other needed arguments later).

To use partial, you must import it from the functools module.

partial() functions can be confusing without a good use case. I personally had a need to use them when I was creating a function to be called under specific condition with specific arguments. I had access to those arguments in only one place, so I used them to build a partial() function that I was able to call later.

Dict Comprehensions in Python lets you quickly generate a dictionary from another iterable, similar to list comprehensions.

[<key_1>: <value_1> for <variable> in <iterable> if <expression_2>]

While doing so, you can optionally perform operations on keys and values going into your dict and also filter them based on conditions.

List Comprehensions in Python lets you quickly generate a list from another iterable.

[<expression_1> for <variable> in <iterable> if <expression_2>]

While doing so, you can optionally perform operations on arguments going into your list and also filter them.

Remember that even though we are calling this "List Comprehensions" we can simply transform them into:

• Tuple Comprehensions - simply replace [] with (). Important - Even though we are calling it a "tuple" comprehension, this will create a generator.

• Set Comprehensions - simply replace [] with {}. As you guessed, Set Comprehensions will create set so it will delete duplicates.

all(iterable) returns True if all objects in provided iterable are "truthy".

If every item evaluates to True, all() returns True. If even one item is "falsy" (evaluating to False), all() returns False.

Important - If the iterable is empty, all() returns True by default!

In Python, values like 0, None, [], {}, "", and () are "falsy" and evaluate to False. Any non-zero numbers, non-empty containers, and most other objects are considered "truthy." A truthy objects returns True after calling bool(object).

any(iterable) returns True if any object in provided iterable is "truthy".

That means that if at least one item evaluates to True, any() returns True. If all items are "falsy" (evaluating to False) (or if the iterable is empty), any() returns False.

In Python, values like 0, None, [], {}, "", and () are "falsy" and evaluate to False. Any non-zero numbers, non-empty containers, and most other objects are considered "truthy." A truthy objects returns True after calling bool(object).

sum(iterable, start=0) simple function that will sum up provided iterable (such as a list or tuple) and return result. This function is primarily intended for use with numeric data.

sum() accepts optional argument start that will be also added to the sum or returned as a default if iterable is empty.

min(iterable_1, ..., key=func, default=obj) returns the smallest item from a single iterable or the smallest of two or more arguments.

Accepts optional key-word key argument that needs to be a function that will be used to evaluate each item's number/value.

With two or more arguments provided, min() will return the smallest one. If two elements or arguments have the same value min() will return the first one found.

min() also accepts optional key-word default argument that will be returned if provided iterable is empty.