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Alright, so we've seen that we can
have a Python installation that's

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separate from our main installation.
So how do we know which Python will be

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used when we run our program?
The answer to that is, our main

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installation will be used by default.
Now we can easily confirm that.

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We didn't install colorama
in our main installation of Python,

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so therefore our code should crash 
when we run it.

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So switching back to the command line, or
terminal session, from a couple of

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videos ago, and you can see, I've still got mine open

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from a few videos ago. So you should
still be in your project directory.

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If not, maybe because you've closed down
the command prompt since then,

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repeat the earlier steps to change back
into your project directory.

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In my case, you can still see that I'm
still there. So if you need to do that,

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refer to your notes on how to do
that. You did take notes, didn't you?

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Right? If not, watch the video, running
your program like a user again,

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and take notes this time. Alright. So
I'm in my project directory, and I'm

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going to run my colour print
program. So I'm just going

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to, basically, use an up arrow here,
and you can see the comment at the

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bottom of the screen there;
python colour_print.py.

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And just a note here, as a
reminder to use python 3,

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if you've also got python 2 installed. In
my case, we established that I've got

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python 3 only. I'm gonna press
enter there, and you can see

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we've got an error.
So the program's crashed when we try

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to import colorama, on line 1;
No module named colorama. That's good

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because we've confirmed that we didn't
alter the main installation of Python,

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when we installed the colorama package.
When we run our programs in an IDE,

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the IDE activates the virtual
environment for us.

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We're running now from a command prompt,
so we have to activate the virtual

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environment ourselves.
So going back to our IDE again,

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I'm just going to quickly run it again
so we've got the run pane.

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And the very first line, it shows
the complete path to the Python

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interpreter.
That's very useful, because that's the

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Python interpreter that we want to
activate.

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Make a note of that path because we're
going to need it to activate the virtual

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environment.
you can copy the link to the clipboard

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but be careful - the link's clickable and will
launch Python if you click it. I find it

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easier just to click the mouse just to
the left of the path, over here,

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and just use the shift and the right arrow
that I'm using there, to select the path.

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Now there's a trick to doing that so that Python

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doesn't run. Move the mouse
very slightly sideways before releasing

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the mouse button,
but if you can't get the hang of it,

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don't worry - just close the
python window that appears.

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The cursor will be in the correct place,
and you can use the keyboard to select

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the path.
Ctrl-C will then copy it to the clipboard.

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Alright, so we'll just go back
because what we actually want to do,

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is select up to, but
not including python.exe, or whatever it

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says after that slash.
Basically, we don't want to copy the

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python from the end, so stop
after the last backslash,

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on windows which I'm running now,
or slash on Mac and Linux.

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And the reason for that is we want to
activate this and it's done slightly

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differently on Windows, and Linux or Macs.

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Alright, so I'm back here in my command prompt.

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I'm going to paste in the path that I just copied,

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and that's the path for me. Now we need
to add a backslash and

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activate to the end of that. Now you'll
do something similar on Linux and Mac,

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but remember to type source and a space first.

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Once we've done that, we're now using the
Python installation

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for your virtual environment. Note now,
that the prompt has changed.

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In my case, I've got parentheses venv

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at the start of the prompt, but you may
have something different like python 38,

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or something along those lines.
The bottom line is, with those

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parentheses, it indicates that you're
using a virtual environment

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to run our programs. Something else to
know is, you no longer have to run

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python3. Whichever version of python you

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installed in the virtual environment,
you run them all with the command python

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in the virtual environment.
Alright, so let's see this working,

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but try working now, python colour_print.py,

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and we get our output in glorious
technicolor on a Windows 10 computer,

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as you can see. Yay. Now it still 
also works on Linux and Mac computers.

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Alright, so once you've finished using

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your virtual environment, the command to deactivate

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is the same on all three operating systems,
and it's literally the word deactivate.

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I didn't need to specify a path there
because activating

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took care of that for us.

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Alright, so I'm going to close my command prompt now,

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and I'll see you in the next video.