<human>:  lost focus event in the browser.
<bot>: Here is a Python program to lose focus event in the browser

import webbrowser

def lost_focus(event):
  """Handle lost focus event"""
  print("lost focus")

# Enter the event
event = webbrowser.open("http://www.google.com")

# Calling the function
print((lost_focus(event)))

#Example Output
# lost focus
# None

#Remember to inspect code for bugs.