Tables of contents are well written and structured the notebooks in a nice manner.
However, the content of the notebook would be more user-friendly if there would be "back to top" link beside the titles inside the notebook. #4

Hello., Greeting,

In the “Imperative _ Declarative programming” diagram, in the first part of OOP tutorial, two items, “Procedural” and “Object-oriented”, are mistakenly placed under the “Declarative” category, and two items, “Logic” and “Functional”, are placed under the “Imperative” category, that must turned into the following respectively:

Imperative programming paradigm:

1. Procedural programming paradigm
2. Object-oriented programming paradigm
   .. ./

Declarative programming paradigm:

1. Logic programming paradigm
2. Functional programming paradigm
   .. ./

Add some examples for the Serialization topic in the YAML document about the tags.
!!map
!!seq
!!str
!!null
!!bool
!!int
!!float

Hi friends, I wanna update dictionary file and add three informative and useful methods with their examples.

get()

for getting value of a key in dictionary

update()

for updating a dictionary with other dictionary

and
setdefault()

get or update a dictionary

Also I can add other methods but I think these are very important, so if you think same, please let me send PR and commit.
thanks

In README.md, there are some links that are not available, and the response is 404. That happened because of the not updated names.
The links are mentioned here:

• Pure Programming

  • ❌ Python
  • ❌ Data Structure

• Operating Systems

  • ❌ Linux

• Database Tools

  • ❌ Git

• Data Science

  • ❌ Introduction
  • ❌ Linear Algebra
  • ❌ Statistics

I tried to modify them:

- ## Pure Programming
    - [Python](01.%20Python)
    - [Data Structure](03.%20Data%20Structure%20and%20Algorithm)

- ## Operating Systems
    - [Linux](02.%20Linux)

- ## Database Tools
    - [Git](05.%20Git)

- ## Data Science
    - [Data Processing](04.%20Data%20Science/02.%20Data%20Processing)
    - [Statistics](04.%20Data%20Science/03.%20Statistics)
    - [Linear Algebra](04.%20Data%20Science/04.%20Linear%20Algebra)   

⚠️ Note
There is no Introduction in your 04. Data Science directory. I replaced it with 02. Data Processing