How to make Python 2.7 and Python 3.1 coexist on windows 7?
<p>I have a Python 3.1 installed on my desktop but now I need to have Python 2.7 to run CQL. I installed both versions Python on my box, type 'Python', the 3.1 version was invoked. but when I tried to use 2.7 version by specified the path of the executable of 2.7, the 3.1 was invoked again, with some errors, as listed below:</p>

<pre><code>C:\Python27&gt;.\python.exe
Traceback (most recent call last):
  File "C:\Python31\lib\site.py", line 56, in &lt;module&gt;
    import os
  File "C:\Python31\lib\os.py", line 380, in &lt;module&gt;
    from _abcoll import MutableMapping  # Can't use collections (bootstrap)
  File "C:\Python31\lib\_abcoll.py", line 54
    class Hashable(metaclass=ABCMeta):
                        ^
SyntaxError: invalid syntax
</code></pre>

<p>what should/could I do to make both Python version work for me?</p>
