input: 
  from flask import Flask, render_template, request, redirect
  import sqlite3
  
  app = Flask(__name__)
  
  @app.route('/')
  def home():
      return render_template('index.html')
  
  @app.route('/submit', methods=['POST'])
  def submit():
      """Process form data submission for Name, Email, and Phone, and store it in a SQLite database.
      >>> # Assuming the form is submitted with the following data
      >>> # Name: 'John Doe', Email: 'john@example.com', Phone: '1234567890'
      >>> submit()  # Simulating the POST request
      >>> # Check if the data is inserted correctly into the database
      >>> conn = sqlite3.connect('data.db')
      >>> cur = conn.cursor()
      >>> cur.execute("SELECT * FROM data WHERE name='John Doe'")
      >>> result = cur.fetchall()
      >>> conn.close()
      >>> result[0] == ('John Doe', 'john@example.com', '1234567890',)
      True
      """
      name = request.form.get('name')
      email = request.form.get('email')
      phone = request.form.get('phone')
      
      conn = sqlite3.connect('data.db')
      cur = conn.cursor()
      
      cur.execute("INSERT INTO data (name, email, phone) VALUES (?, ?, ?)", (name, email, phone))
      conn.commit()
      
      return redirect('/')
      
  if __name__ == '__main__':
      app.run(debug=True)
  
output:     conn.close()