mutagen uninstallable? I cannot understand this:

pip install mutagen


returns no error, yet as I try to use it I get this:

$ python
Python 2.6.6 (r266:84292, Jun 22 2011, 22:27:57) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
&gt;&gt;&gt; import mutagen
Traceback (most recent call last):
  File "&lt;stdin&gt;", line 1, in &lt;module&gt;
ImportError: No module named mutagen


what is happening?
On my Macbook Pro running Sierra, it is not installed.  However if it is, you should be able to remove it with pip remove mutagen, and reinstall it with pip install mutagen. It should automatically download, build and install mutagen.  Also, make sure your python is updated to the latest version (i. e. 2.7.10).  If not, you may want to install Homebrew and upgrade it through that. 

Homebrew can be installed by /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)", and python can be updated with brew update; brew upgrade.

Link to Homebrew's official website