input: Write a python function to create a Flask route to update a product's price.
  assert update_product_price(1, 19.99) == {'message': 'Product price successfully updated.'}
  assert update_product_price(2, 29.99) == {'message': 'Product price successfully updated.'}
  assert update_product_price(3, 39.99) == {'message': 'Product price successfully updated.'}
output: from flask import Flask, request, jsonify
  
  app = Flask(__name__)
  
  # Dummy database of products
  products = {
      1: {'name': 'Product 1', 'price': 10.00},
      2: {'name': 'Product 2', 'price': 20.00},
      3: {'name': 'Product 3', 'price': 30.00},
  }
  
  @app.route('/update_price/<int:product_id>', methods=['PUT'])
  def update_product_price(product_id):
      if product_id in products:
          new_price = request.json.get('price')
          if new_price is not None and isinstance(new_price, (int, float)):
              products[product_id]['price'] = new_price
              return jsonify({'message': 'Product price successfully updated.'})
          else:
              return jsonify({'error': 'Invalid price provided.'}), 400
      else:
          return jsonify({'error': 'Product not found.'}), 404
  
  if __name__ == '__main__':
      app.run(debug=True)