input: 
  from flask import Flask, render_template, request, redirect
  import sqlite3
  
  def create_flask_app(form_input: dict) -> str:
      """This function creates a Flask application that accepts form data (name, email, phone) 
      and stores it in a SQLite database. It returns a string indicating the success of the storage operation.
      >>> create_flask_app({'name': 'John Doe', 'email': 'john@example.com', 'phone': '1234567890'})
      'Data successfully stored!'
      >>> create_flask_app({'name': '', 'email': '', 'phone': ''})
      'Data storage failed!'
      """
      app = Flask(__name__)
  
      @app.route('/')
      def home():
          return render_template('index.html')
  
      @app.route('/submit', methods=['POST'])
      def submit():
          name = request.form.get('name')
          email = request.form.get('email')
          phone = request.form.get('phone')
          
          if name and email and phone:
              conn = sqlite3.connect('data.db')
              cur = conn.cursor()
              cur.execute("INSERT INTO data (name, email, phone) VALUES (?, ?, ?)", (name, email, phone))
              conn.commit()
              conn.close()
              return 'Data successfully stored!'
          else:
              return 'Data storage failed!'
          
      return app
  
output:     app.run(debug=False)