So I was give the task to write a code to get the union of two sets. And i wrote the the following 2 versions of codes.

**Version 1**

```
###### Set_Input ########
set_1=input().split(" ")
set_2=input().split(" ")
set_union=set_1+set_2
###### Set_Union_Logic ########
for i in set_union:
if set_union.count(i)>1:
set_union.remove(i)
print(set_union)
```

**Version 2**

```
###### Set_Input ########
set_1=input().split(" ")
set_2=input().split(" ")
set_union=set_1+set_2
###### Set_Union_Logic ########
for i in set_union:
if set_union.count(i)>1:
set_union= set_union.remove(i)
print(set_union)
```

Version 1 works fine but Version 2 gives me the following error

```
if set_union.count(i)>1:
AttributeError: 'NoneType' object has no attribute 'count'
```

Can any one explain why writing * set_union= set_union.remove(i)* in the loop causes this error.

Thanks in advance.