#Illustrate lexical scoping

def incr(x):
    # Since first use of increment defines a value for it
    # Python introduces a new variable
    increment = 3
    x = x + 3
    return x

def decr(x):
    # Note that value of variable increment has not been locally defined
    # Python will search in enclosing scope for this variable
    x = x - increment
    return x

increment = 1
print 'Test scope rules'
x = 10  #Create a new variable x and bind it to the int 10
print x
print incr(x)
print x # Note that value of x is unchanged by call to incr
print decr(x)