input: def fetch_data_from_db():
      """Fetches data from an SQL database and presents the data in the form of a JSON.
      
      The function connects to a SQLite database named 'database.db', retrieves all records from the 'users' table,
      and returns the data in JSON format.
      
      Example:
      The 'users' table contains the following records:
      | id | name   | email             |
      |----|--------|-------------------|
      | 1  | Alice  | alice@example.com |
      | 2  | Bob    | bob@example.com   |
      | 3  | Charlie| charlie@example.com |
  
      >>> fetch_data_from_db()
      [{"id": 1, "name": "Alice", "email": "alice@example.com"}, {"id": 2, "name": "Bob", "email": "bob@example.com"}, {"id": 3, "name": "Charlie", "email": "charlie@example.com"}]
      """
      import json 
      import sqlite3
      from flask import Flask, request, jsonify 
  
      app = Flask(__name__) 
        
      def dict_factory(cursor, row):
          d = {}
          for idx, col in enumerate(cursor.description):
              d[col[0]] = row[idx]
          return d 
        
      @app.route('/', methods=['GET'])
      def index(): 
          connection = sqlite3.connect('database.db')
          connection.row_factory = dict_factory
          cur = connection.cursor() 
          all_users = cur.execute('SELECT * FROM users;').fetchall() 
          return jsonify(all_users) 
        
      if __name__ == '__main__': 
          app.run(debug = True)
output:     connection = sqlite3.connect('database.db')
      connection.row_factory = dict_factory
      cur = connection.cursor()
      all_users = cur.execute('SELECT * FROM users;').fetchall()
      connection.close()
      return json.dumps(all_users)