Run below program in Python and explain

1.

F = raw_input("Enter a temperature in Fahrenheit: ")

F = float(F)

C = 5 / 9. * (F - 32)

print "%g Fahrenheit = %g Celsius" % (F, C)

2.

import sys

F = float(sys.argv[1])

C = 5 / 9. * (F - 32)

print "%g Fahrenheit = %g Celsius" % (F, C)

3.

import sys

try:

F = float(sys.argv[1])

except IndexError:

print 'You failed to provide a temperature in Fahrenheit '\

'as input on the command line!'

sys.exit(1)# abort

C = 5. / 9 * (F - 32)

print "%g Fahrenheit = %g Celsius" % (F, C)