What you suggest actually works as is:
>>> x=1
>>> eval(input())
print(x)
1
Another method you can have a look at is the exec method (and above that is a detailed description for eval).
Depending on what you are going for this might be a bad idea though. Have a look at the local
and global
parameters to restrict the environment.
solved How do I execute code that is taken as user input? [closed]