modules that ship with Perl, namely DB_File, GDBM_File, NDBM_File,
ODBM_File and SDBM_File.
-Each of the methods work identically, and are used to install (or
+Each of the methods works identically, and is used to install (or
uninstall) a single DBM Filter. The only difference between them is the
place that the filter is installed.
You can use any combination of the methods from none to all four.
All filter methods return the existing filter, if present, or C<undef>
-in not.
+if not.
To delete a filter pass C<undef> to it.