input: 
  from flask import Flask, render_template, request, redirect
  import sqlite3
  
  def submit_form(name: str, email: str, phone: str) -> None:
      """
      Submits form data (name, email, phone) and stores it in a SQLite database.
      >>> submit_form('John Doe', 'john@example.com', '1234567890')
      >>> # Check if the data is correctly inserted in the database.
      """
  
output:     conn = sqlite3.connect('form_data.db')
      cursor = conn.cursor()
      cursor.execute('''CREATE TABLE IF NOT EXISTS submissions
                        (name TEXT, email TEXT, phone TEXT)''')
      cursor.execute("INSERT INTO submissions (name, email, phone) VALUES (?, ?, ?)", (name, email, phone))
      conn.commit()
      conn.close()