input: Write a function to create a web server using the Flask framework in Python that serves a JSON object containing the current temperature for a city based on the city name provided in the request. The function should use an external API to fetch the temperature data.
  assert create_web_server() != None
  assert create_web_server().route('/getTemp', methods=['POST']) != None
  assert create_web_server().run != None
output: from flask import Flask, request, jsonify
  import requests
  
  def create_web_server():
      app = Flask(__name__)
  
      @app.route('/getTemp', methods=['POST'])
      def get_temp():
          city = request.json.get('city')
          api_key = 'your_api_key_here'
          url = f'http://api.openweathermap.org/data/2.5/weather?q={city}&appid={api_key}&units=metric'
          response = requests.get(url)
          data = response.json()
          temperature = data['main']['temp']
          return jsonify({'temperature': temperature})
  
      return app