Python -- Opening multiple tabs using Selenium

try like this for python:

browser=webdriver.Chrome()
browser.get('http:/reddit.com')
window_before = driver.window_handles[0]
browser.find_element_by_tag_name('body').send_keys(Keys.CONTROL + 't')
window_after = driver.window_handles[1]
driver.switch_to_window(window_after)
time.sleep(3)
browser.get('http://bing.com')

To interact with a window, you need to set the context to that window with driver.switch_to.window. It would also be easier to open a new tab with a script injection:

browser=webdriver.Chrome()

#first tab
browser.get('http:/reddit.com')

#second tab
browser.execute_script("window.open('about:blank', 'tab2');")
browser.switch_to.window("tab2")
browser.get('http://bing.com')