Delete repeated digits X89842

Statement

Write a function @del_rep_dig(s)@ that has a string $s$ as parameter and returns the string obtained after ruling out all the digit repetitions.

Sample session

>>> del_rep_dig('boeing727')
'boeing72'
>>> del_rep_dig('00705007')
'075'
>>> del_rep_dig('12gold31234')
'12gold34'

Information