####Some good uses of tuples:

####switching variables without using a third variable
##a = 1
##b = 2
##a,b = b,a
##print("after switch, a =", a, "and b =", b)

####Fibonacci numbers without a next variable
##x = int(input("enter an integer"))
##a = 1
##b = 1
##while b<x:
##    print(b, end=" ")
##    a, b = b, a+b
##print("The smallest Fibonacci number greater or equal to", x, "is", b)

####passing coordinates to and from functions
##def distance_to_origin(point):
##    total = 0
##    for x in point:
##        total += x ** 2
##    return total ** 0.5
##
##print("distance from origin to (3,4) is", distance_to_origin( (3,4) ) )
##print("distance from origin to (3,4,5) is", distance_to_origin( (3,4,5) ) )



####Mutable objects can be changed through multiple names
####and references.  This may cause confusion.  Try to
####predict the output of the following scripts

####Multiple aliases
##a_list=[1]
##b_list=a_list
##b_list.append(2)
##print(a_list)

####Object in two namespaces
##def pirate(l):
##    l.append("R")
##    l = ["Matey"]
##    return l
##l = ["A"]
##pirate(l)
##print(l)

####Multiple containment
##a_list = []
##b_list = [a_list, a_list]
##c_list = [a_list]
##c_list[0].append("aye")
##print(b_list)

####circular references
##a_list = [2]
##a_list.append(a_list)
##print(a_list)

####Reference cycle
##a_list = [2]
##b_list = [a_list]
##a_list[0] = b_list
##print(a_list)

####AJ's example
##test = [1,[1,2],[1,2,3],[1,2,3,4]]
##test.append(test)
##print(test.index(test))
##if test in test:
##    print("test is in test")
##print(test.index([1,[1,2],[1,2,3],[1,2,3,4]] ))


####Function used in the checker class exercise
##def print_board(board):
##    """Displays a board made up of a list of rows,
##        where each row is a list of ints"""
##    for row in board:
##        for item in row:
##            print("{:3d}".format(item), end=" ")
##        print()


####Demonstrates basic dictionary operations
##x = {}
##print("x is an empty dict:", x)
##y = { "Paul" : "Pawel", "likes":"lubi" }
##print("a dictionary for translating:",y)
##
###adding an element
##y["computers"] = "komputery"
##print("looking up y['computers']:", y["computers"])
##
###length of a dict
##print("y has", len(y), "keys")
##
###testing membership
##print("checking if 'Paul' is in y:", "Paul" in y)
##print("checking if 'Bob' is in y:", "Bob" in y)
##
###dicts are iterable
##for key in y:
##    print(key, "translated is", y[key])
##
###iterating through values is a bit trickier
##print("the values in y: ", end="")
##for value in y.values(): #y.values returns an iterable called a view
##    print(value, end=" ")
##
###can also iterate through keys and values at the same time
##print("the key-value pairs in y: ", end="")
##for key, value in y.items(): #also returns an iterable called a view
##    print(key,", which translates to", value)
##
##
###A short translation script
##msg = "Paul really likes to program computers"
##m_list = msg.split() #creates a list of words
##
#### Add code to check if each word in m_list is in y.
#### If it is, replace it with its value in y.
##
##msg= " ".join(m_list)  #glues a list of strings back together
##print(msg)