How to Check if user has access for a given taxonomy?

I'm going mad here... From the documentation:

There are two ways you can check whether or not a user has
access for a given taxonomy.

First, you can call node_access() on a given node
and if taxonomy_access module is enabled it will take category permissions into
account when determining whether or not the user has access to the given node.

The second way is to call the function taxonomy_access() which takes two
parameters, an operation and a taxonomy, with a third optional paramater of a
userid to use instead of the current user. It returns whether or not the user
is authorized, almost identical to node_access().

I tried called taxonomy_access, and got a "Call to undefined function" error. Checked the module code, and sure enough, that function doesn't exist. How does one perform a simple programmatic check to see whether the current user has access to a given taxonomy term?

Any help would be oh so much appreciated.