I have a list of codes, eg:
KMDE1
DFER0
DCMF1
DFER0
FRRT4
KMDE1
TGRY3
KMDE1

Is there a quick way I can produce a summary list of these codes, showing
all the codes that appear ie. no duplicates. So for this example, it would be
KMDE1
DFER0
DCMF1
FRRT4
TGRY4