#!/usr/bin/env python

"""
   Parameters in Python are passed by value. 
   We need to have in mind the following:
    1- The parameter passed in is actually a reference to a 
       variable (but the reference is passed by value)
    2- Some data types are mutable, but others aren't
"""

# Example 1: String - an immutable type
#            There's nothing we can do to change the contents of the string.
#            A tring parameter is passed by value, assigning a new string 
#            to it within the function has no effect. The string inside
#            the function is a copy of the original string.

def try_to_change_string_reference(the_string):
    print 'got', the_string
    the_string = 'In a kingdom by the sea'
    print 'set to', the_string

outer_string = 'It was many and many a year ago'

print 'before, outer_string =', outer_string
try_to_change_string_reference(outer_string)
print 'after, outer_string =', outer_string