''' Purpose: introduce variable manipulation through assignment
'''

print( )

# first generation there are 2 rabbits. each successive
# generation doubles the number of rabbits

nbr_rabbits = 12  # the value of 2 has been assigned to the label/identifier nbr_rabbits
generation  = 1
# these identifiers are being assigned to literal values right now

print( 'Generation: ', generation  ) # 1
print( 'rabbits:    ', nbr_rabbits ) # 2
print( )

# next generation

nbr_rabbits = nbr_rabbits * 2 # you can update the values of variables
generation  = generation + 1 # check the previous value of generation and then add one to it
                                # and set that new value to be represented by the identifier "generation"
# once something's been updated,
    # the original value is lost

print( 'Generation: ', generation  ) # 2
print( 'rabbits:    ', nbr_rabbits ) # 4
print( )

# next generation

nbr_rabbits *= 2 # same as nbr_rabbits = nbr_rabbits * 2
generation += 1  # same as generation  = generation + 1

# nbr_rabbits = ... # ... is a placeholder for code
# generation  = ...

# next generation

print( 'Generation: ', generation  )
print( 'rabbits:    ', nbr_rabbits )
print( )

nbr_rabbits = nbr_rabbits * 2
generation  = generation + 1

# next generation

print( 'Generation: ', generation  )
print( 'rabbits:    ', nbr_rabbits )
print( )

# typical updating
# start_value = something
# start_value = start_value + ____  OR start_value * ______

# the = in Python is the assignment operator
# identifier = value   sets identifier to be a label representing value
    # (technically identifier "points to" value in memory, but more on this in later CS classes)


# how do I make this go on for a long while?
# use a for loop! MORE ON THIS LATER!!!!!!! Don't worry too much about it now.
# looping means you can repeat an action...
# MORE ON THIS LATER, but the takeaway for now is that loops help us repeat actions
# nbr_rabbits = 2
# generation  = 1
# n = 100
# for i in range(0, n):
#     nbr_rabbits = nbr_rabbits * 2
#     generation = generation + 1
#     print("Generation:", generation)
#     print("Number of rabbits:", nbr_rabbits)

# how to only run certain pieces of code? - if statements help us make decisions of which code to run...more on this later!