input: from typing import Dict, Union
  
  def create_read_users_api(app, mysql) -> None:
      """ Creates and returns a REST API for creating and reading users using Flask and MySQL.
      The API should have endpoints for:
      1. Creating a user using a POST request to '/users'.
      2. Reading all users using a GET request to '/users'.
      3. Reading a single user by ID using a GET request to '/users/<id>'.
      
      >>> app = Flask(__name__)
      >>> app.config['MYSQL_USER'] = 'root'
      >>> app.config['MYSQL_PASSWORD'] = 'password'
      >>> app.config['MYSQL_DB'] = 'users'
      >>> app.config['MYSQL_CURSORCLASS'] = 'DictCursor'
      >>> mysql = MySQL(app)
      >>> create_read_users_api(app, mysql)
      >>> # Assuming the database has users with ids: 1, 2, 3 and names: 'Alice', 'Bob', 'Charlie' respectively.
      >>> response = app.test_client().get('/users/2')
      >>> response.get_json()
      {'id': 2, 'name': 'Bob', 'email': 'bob@example.com'}
      """
  
      
      @app.route('/users', methods=['POST'])
      def create_user():
          name = request.json['name']
          email = request.json['email']
  
          cur = mysql.connection.cursor()
          cur.execute("INSERT INTO users (name, email) VALUES (%s, %s)", (name, email))
          mysql.connection.commit()
          cur.close()
  
          return jsonify({'message': 'User created'})
  
      @app.route('/users', methods=['GET'])
      def get_users():
          cur = mysql.connection.cursor()
          cur.execute("SELECT * FROM users")
          users = cur.fetchall()
          cur.close()
  
          return jsonify(users)
  
      @app.route('/users/<id>', methods=['GET'])
      def get_user(id):
          cur = mysql.connection.cursor()
          cur.execute("SELECT * FROM users WHERE id=%s", (id,))
          user = cur.fetchone()
          cur.close()
  
          return jsonify(user)
      
      return None
output:     @app.route('/users/<id>', methods=['GET'])
      def get_user(id):
          cur = mysql.connection.cursor()
          cur.execute("SELECT * FROM users WHERE id=%s", (id,))
          user = cur.fetchone()
          cur.close()
  
          if user:
              return jsonify(user)
          else:
              return jsonify({'message': 'User not found'}), 404