The usage of the methods provided here is simple. You always provide
a sorted list to any of these methods and accept a sorted list of
values in return.

Suppose @lis1 and @list2 are two available lists defined as
follows:

@list_1 = qw ( first list of values );
@list_1 = qw ( second list of values );

and we run the following commands:

my @output_1 = uniq sort @list1 @list2;
my @output_2 = distinct sort @list1 @list2;
my @output_3 = dups sort @list1 @list2;


Now @output_1 has qw( first list of second values )
@output_2 has qw( first second )
and @output_3 has qw( list of values )

Thus @output_1 has all values from either input lists sans any
redundant values. @output_2 has exactly those values that appear
at most once in combined list. On the other hand @output_3 has
a list of values that appear multiple times in input.

EXPORT
Exported are methods
1) uniq [ similar to 'uniq' shell command ]
2) distinct [ similar to 'uniq -u' shell command ]
3) dups [ similar to 'uniq -d' shell command ]