=head1 DESCRIPTION

=over 4

=for diagnostics
start items

=item from undefined

The first file name you sent to the comparison function was undefined.

=item to undefined

The second file name you sent to the comparison function was undefined.

=item Third arg to compare_text() function must be a code reference

If the standard string comparison does not match your needs, you can
provide a code reference as a third argument to the C<compare_text> function.
You provided something else. Check your program.

=item Usage: compare( file1, file2 [, buffersize])

You must call the C<compare> function with two file names or two filehandles,
and optionally a buffer size.

=item Usage: compare_text( file1, file2 [, cmp-function])

You must call the C<compare_text> function with two file names or two filehandles,
and optionally a comparison function.

=back