## Python API Framework: A Comprehensive Guide

### Introduction
In the world of software development, APIs are an essential component for building applications that can communicate with each other. Python, being a versatile and popular programming language, offers various frameworks for creating APIs. In this article, we will explore how to build a Python API framework from scratch using the Flask framework.

### Step-by-Step Guide to Building a Python API Framework

| Step | Description |
|------|-------------|
| 1. | Install Flask: Flask is a lightweight WSGI web application framework. It is easy to install using pip. |
| 2. | Create a Flask App: Initialize a Flask app and define the routes. |
| 3. | Define API Endpoints: Create endpoints for different functionalities of the API. |
| 4. | Implement API Functionality: Define the logic for each endpoint. |
| 5. | Run the Flask App: Test the API by running the Flask app. |

### Step 1: Install Flask
```python
pip install flask
```
This command installs the Flask framework in your Python environment.

### Step 2: Create a Flask App
```python
from flask import Flask

app = Flask(__name__)

if __name__ == '__main__':
app.run(debug=True)
```
In this code snippet, we import the Flask class and initialize a Flask app. The `if __name__ == '__main__':` block ensures that the app runs only when executed directly.

### Step 3: Define API Endpoints
```python
@app.route('/')
def home():
return 'Welcome to the Python API Framework!'

@app.route('/api/data', methods=['GET'])
def get_data():
return {'message': 'This is a sample API endpoint'}
```
These route decorators define the endpoints for the API. The `@app.route('/')` decorator sets the root endpoint, while `@app.route('/api/data')` sets the `/api/data` endpoint with a GET method.

### Step 4: Implement API Functionality
```python
from flask import request

@app.route('/api/add', methods=['POST'])
def add_numbers():
data = request.get_json()
num1 = data['num1']
num2 = data['num2']
result = num1 + num2
return {'result': result}
```
In this code, we define an endpoint `/api/add` with a POST method to add two numbers sent in the request body.

### Step 5: Run the Flask App
```bash
python app.py
```
Run the Flask app by executing the Python script. The output will provide the URL where the Flask app is running locally.

### Conclusion
In this article, we discussed the process of building a Python API framework using the Flask framework. By following the steps outlined above, you can create a basic API with endpoints and functionalities. It is important to explore further features of Flask and best practices in API development to build robust and scalable APIs. Happy coding!