how to find out the version of a certain installed package

Hi,

In a projecet I'm making using pycrypto, I need to find out the
current installed version of pycrypto. After looking around, I found
out that "pkg_resources.requires("pycrypto") will give me a string
containing the version number, but is this the only way to do it or
are there other ways?

thanks,

Christophe
.