"""
Ex 4.2 from "A primer on..." 
Read the temperature in Fahrenheit as a 
command line argument, convert to Celsius 
and print to screen.
"""

import sys

#command line arguments are in the list sys.argv
F = float(sys.argv[1])

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

print(f'{F} grader Fahrenheit er {C:.1f} grader Celsius')
"""
Terminal> python f2c_cml.py 100
100.0 grader Fahrenheit er 37.8 grader Celsius
"""