driver = webdriver.Firefox()
File "C:\Python27\lib\site-packages\selenium\webdriver\firefox\webdriver.py", line 145, in __init__
self.service.start()
File "C:\Python27\lib\site-packages\selenium\webdriver\common\service.py", line 81, in start
os.path.basename(self.path), self.start_error_message)
WebDriverException: Message: 'geckodriver' executable needs to be in PATH.