# We just saw a Python program file named types.py.  That is a Python
# script file. 

# If you run that script in script mode, i.e., run it like this:
#
#     alee$ python types.py
#
# it will run fine, but you won't see any output on your screen.

# We can change that by using the 'print' command in Python.
# This time run this program (print.py) in script mode, like this:
#
#     alee$ python print.py
#
# and see what you get on the screen.

3 + 4 + 2       # Line 1

print 4 + 8     # Line 2

# The python interpreter in script mode will evaluate each line of your
# program (script) and do exactly what you asked it to do.

# Line 1 above tells the interpreter to evaluate the expression (3 + 4 + 2)
# and do nothing else.  So, it will evaluate it and produce 9 and that is
# all it does.

# Line 2 tells the interpreter to evaluate the expression (4 + 8) and 
# print it to the standard output device, which is your compter screen.

# I will prepare script files with the print command sprinkled here and
# there if it would make the program easier to understand when you run it.

# You might wonder what is goind on in an interactive mode as in ipython.
# When Python runs in an interactive mode, the interpreter works a little
# differently in that it interprets line and furthermore prints the result
# to the screen which makes sense since you are sitting there to see the
# result.  When you are in script mode, most likely you will write a
# series of lines of code and many of those lines will be for some 
# intermediate steps of your program.  You wouldn't want to see the
# values of each line printed on the screen.  That will be too confusing.