title: "NameError: name api_key is not defined" when parsing json
body: <p>I'm completing an assignment and having a little bit of trouble. (Very new to this)  I am receiving "<strong><em>NameError: name api_key is not defined</em></strong>" message. The syntax in this cell is as follows:</p>
  
  <pre><code>record = 0
  for index, row in location_data.iterrows():
      city_name = row['city']
      country_code = row['country']
      url = target_url + city_name + ',' + country_code + '&amp;units=' + units + '&amp;APPID' + api_key
      print (url)
      try: 
          weather_response = req.get(url)
          weather_json = weather_response.json()
          latitude = weather_json["coord"]["lat"]
          longitude = weather_json["coord"]["lon"]
          temp = weather_json["main"]["temp"]
          humidity = weather_json["main"]["humidity"]
          cloud = weather_json["clouds"]["all"]
          wind = weather_json["wind"]["speed"]
          location_data.set_value(index,"Temp", temp)
          location_data.set_value(index,"Humidity",humidity)
          location_data.set_value(index,"Wind Speed", wind)
          location_data.set_value(index,"Cloudiness",cloud)
          location_data.set_value(index,"Lat", latitude)
          location_data.set_value(index,"Longitude",longitude)
          print("Retrieved data for %s, %s" % (city_name, country_code))
      except:
          print("No data for %s, %s" % (city_name,country_code))
      record += 1
      if record % 59 == 0:
          time.sleep(60)
  </code></pre>
  
  <p>Thank you for any and all help.</p>