input: Write a python function to get the temperature of a city using the OpenWeatherMap API.
  assert get_temp('London')=={'temperature': 289.15}
  assert get_temp('New York')=={'temperature': 295.37}
  assert get_temp('Tokyo')=={'temperature': 303.21}
output: import requests
  
  def get_temp(city):
      api_key = 'your_api_key_here'
      base_url = "http://api.openweathermap.org/data/2.5/weather?"
      complete_url = base_url + "q=" + city + "&appid=" + api_key
      response = requests.get(complete_url)
      data = response.json()
      if data["cod"] != "404":
          main = data["main"]
          temperature = main["temp"]
          return {'temperature': temperature}
      else:
          return {'error': 'City not found'}