input: Write a function to create a Flask application that accepts form submissions with fields 'Name', 'Email', and 'Phone', and stores the submitted data in an SQLite database. The function should return the Flask application object. 
  
  assert create_flask_app().__name__=="__main__"
  assert create_flask_app().url_map.strict_slashes==False
  assert len(create_flask_app().url_map._rules[0].methods)>=2
  assert len(create_flask_app().url_map._rules[1].methods)==1
output: def create_flask_app():
      from flask import Flask, request, render_template_string
      import sqlite3
  
      app = Flask(__name__)
      app.url_map.strict_slashes = False
  
      conn = sqlite3.connect('submissions.db')
      c = conn.cursor()
      c.execute('''CREATE TABLE IF NOT EXISTS submissions
                   (name TEXT, email TEXT, phone TEXT)''')
      conn.commit()
      conn.close()
  
      @app.route('/', methods=['GET', 'POST'])
      def index():
          if request.method == 'POST':
              name = request.form['Name']
              email = request.form['Email']
              phone = request.form['Phone']
              conn = sqlite3.connect('submissions.db')
              c = conn.cursor()
              c.execute("INSERT INTO submissions (name, email, phone) VALUES (?, ?, ?)", (name, email, phone))
              conn.commit()
              conn.close()
              return "Submission successful!"
          return render_template_string('''
              <form method="post">
                  Name: <input type="text" name="Name"><br>
                  Email: <input type="text" name="Email"><br>
                  Phone: <input type="text" name="Phone"><br>
                  <input type="submit" value="Submit">
              </form>
          ''')
  
      return app