input: Write a function to create a Python web application for a car insurance calculator. The application should have a page where the user can input data such as age, gender, car model, etc., and it should return a calculated insurance price. The function should use Flask to create the web application, handle POST requests at the '/calculate' route, and return the calculated insurance price in JSON format.
  assert calculate({'age': 25, 'gender': 'male', 'car_model': 'Sedan'})=={'insurance_price': 0.00}
  assert calculate({'age': 30, 'gender': 'female', 'car_model': 'SUV'})=={'insurance_price': 0.00}
  assert calculate({'age': 40, 'gender': 'male', 'car_model': 'Coupe'})=={'insurance_price': 0.00}
output: 
  from flask import Flask, request, jsonify
  
  app = Flask(__name__)
  
  @app.route('/calculate', methods=['POST'])
  def calculate():
      data = request.json
      age = data.get('age')
      gender = data.get('gender')
      car_model = data.get('car_model')
      
      # Placeholder calculation for insurance price
      insurance_price = 0.00
      
      return jsonify({'insurance_price': insurance_price})
  