input: from typing import Dict
  import json 
  import sqlite3
  from flask import Flask, request, jsonify 
  
  def fetch_sql_data_as_json() -> Dict:
      """
      Fetches all user data from an SQL database and presents the data in the form of a JSON.
      The function sets up a Flask API that, upon GET request, connects to an SQLite database,
      fetches all rows from the 'users' table, and returns them as a JSON.
      
      Example:
      >>> response = fetch_sql_data_as_json()
      >>> isinstance(response, dict)
      True
      """
      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)
      
      return fetch_sql_data_as_json()
output:     with app.test_request_context('/'):
          response = index()
          return json.loads(response.get_data(as_text=True))