idxfti
        ----------+--------------------------+---------------+-----------------------   
                69 | Attempt for dropatsymbol | Test@test.com | 'test':1 'test.com':2
        (1 row)
</pre>
Notice that the string content was passed throught the stored
procedure dropatsymbol. The '@' character was replaced with a
single space ... and the output from the procedure was then stored
in the tsvector column.
<p>This could be useful for removing other characters from indexed
text, or any kind of prep