title: How To Fix "TypeError: 'NoneType' object is not callable"
body: <p>When I run my script:</p>
  
  <pre><code>from selenium import webdriver
  # from selenium.webdriver.firefox.firefox_binary import FirefoxBinary
  from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
  import os
  import pytest
  import unittest
  from nose_parameterized import parameterized
  
      class multiBrowsers(unittest.TestCase):
          @parameterized.expand([
              ("chrome"),
              ("firefox"),
          ])
  
          def setUp(self, browser):
  
              if browser == "firefox":
                  caps = DesiredCapabilities.FIREFOX
                  caps["marionette"] = True
                  caps["binary"] = "/Applications/Firefox.app/Contents/MacOS/firefox-bin"
                  self.driver = webdriver.Firefox(capabilities=caps)
              elif browser == "chrome":
                  self.driver = webdriver.Chrome()
  
          def test_loadPage(self):
              driver = self.driver
              driver.get("http://www.google.com")
  
          def tearDown(self):
              self.driver.quit()
  </code></pre>
  
  <p>I get the error:</p>
  
  <pre><code>Error
  TypeError: 'NoneType' object is not callable
  </code></pre>
  
  <p>I read that I am not passing something correctly but I don't know where to look.  Thanks in advance for the help!</p>