In python selenium, how does one find the visibility of an element?

I found the is_visible method in the Selenium documentation, but I have no idea how to use it. I keep getting errors such as is_visible needs a selenium instance as the first parameter.

Also, what is a "locator"?

Any help would be appreciated.

You should use is_displayed() instead:

from selenium import webdriver

driver = webdriver.Firefox()
driver.get('http://www.google.com')
element = driver.find_element_by_id('gbqfba') #this element is visible
if element.is_displayed():
  print "Element found"
else:
  print "Element not found"

hidden_element = driver.find_element_by_name('oq') #this one is not
if hidden_element.is_displayed():
  print "Element found"
else:
  print "Element not found"