Remove an element from string if it appears twice

Question

I want to remove an element from a string if it appears twice, for example :

str1 = "ggtggt

The output should be" gt"

Answer 1

Out of many ways one way to do it

str1 = "ggtggt"
str2=""
for i in str1:
if i not in str2:
str2+=i

print(str2)

it won't remove element but add non repeating element to new string

Answer 2

A very common way is also to use a set. A set is a data container, but does only allow unique elements. So all duplicated elements will be removed automatically when converting a string to a set:

str1 = "ggtggt"
print(''.join(set(str1)))