def square(x):   ## def means "To define,"
    return x*x   ##return returns an output.
                 ##a function's execution endds when it returns.
def print_rules():
    print("""Sell back your houses at half-price to the bank
Mortage your deeds!
Pay me!""")
##  the main routine or the global frame.
print(square(10))
print(square(2*3 + 5))
print(print_rules())

#print_rules has no input
#It returns the useless default None
#It has a side-effect.  Side-effects are things that are left
#behind when the function executes (other than return value)
#path of execution


#  functions are read into memory.
#  print got called
#  Inside of print, square got called.  Our program jumpst to square
#  square hands 100 to print
#  print puts 100 to the screen.