test_add_contacts (main.ContactsAndroidTests) ... ERROR

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ERROR: test_add_contacts (main.ContactsAndroidTests)

Traceback (most recent call last):
File "./sample-code/examples/python/android_contacts.py", line 23, in setUp
self.driver = webdriver.Remote('http://localhost:4723/wd/hub', desired_caps)
File "build/bdist.linux-x86_64/egg/appium/webdriver/webdriver.py", line 34, in init
super(WebDriver, self).init(command_executor, desired_capabilities, browser_profile, proxy, keep_alive)
File "/usr/local/lib/python2.7/dist-packages/selenium-2.41.0-py2.7.egg/selenium/webdriver/remote/webdriver.py", line 72, in init
self.start_session(desired_capabilities, browser_profile)
File "/usr/local/lib/python2.7/dist-packages/selenium-2.41.0-py2.7.egg/selenium/webdriver/remote/webdriver.py", line 115, in start_session
'desiredCapabilities': desired_capabilities,
File "/usr/local/lib/python2.7/dist-packages/selenium-2.41.0-py2.7.egg/selenium/webdriver/remote/webdriver.py", line 166, in execute
self.error_handler.check_response(response)
File "/usr/local/lib/python2.7/dist-packages/selenium-2.41.0-py2.7.egg/selenium/webdriver/remote/errorhandler.py", line 164, in check_response
raise exception_class(message, screen, stacktrace)
WebDriverException: Message: u"A new session could not be created. (Original error: Could not find AppiumBootstrap.jar; please run 'grunt buildAndroidBootstrap')"

Ran 1 test in 13.123s

FAILED (errors=1)