st: how do you drop repeated values in a variable to remain with only one?

[Gwinyai Masukume <parturitions@gmail.com>]

Dear Stata list,

I have a dataset  with variable A, which has repeated  values:

A
1
2
2
2
3
3
4
5
5
6
6
6

Where the values are repeated e.g 2. I would like to drop the repeated
values and remain with only a single 2.
I have tried the duplicates drop command, but it does not work as the
repeated values are not duplicates, but say different hospital visits by
 the same individual.
I would still like to drop repeated values of the variable A. How can I
do this?

Thanks for your consideration.

Kind regards,
Gwinyai
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/faqs/resources/statalist-faq/
*   http://www.ats.ucla.edu/stat/stata/