input: Write a python function to format the current date and time in the desired format.
  assert format_datetime() == datetime.now().strftime("%A, %d %b %Y %l:%M %p")
  assert format_datetime() == datetime.now().strftime("%Z")
output: def format_datetime():
      from datetime import datetime
      return datetime.now().strftime("%A, %d %b %Y %l:%M %p")