if expression1:
  statement(s)
  if expression2:
   statement(s)
  elif expression3:
   statement(s)
  else
   statement(s)
elif expression4:
  statement(s)
else:
  statement(s)

if expression1:
  statement(s)
  if expression2:
   statement(s)
  elif expression3:
   statement(s)
  else
   statement(s)
elif expression4:
  statement(s)
else:
  statement(s)

#!/usr/bin/python

var = 100
if var < 200:
  print "Expression value is less than 200"
  if var == 150:
   print "Which is 150"
  elif var == 100:
   print "Which is 100"
  elif var == 50:
   print "Which is 50"
elif var < 50:
  print "Expression value is less than 50"
else:
  print "Could not find true expression"

print "Good bye!"

Expression value is less than 200
Which is 100
Good bye!