How to exec() a string like interactive python does?

Tue Jun 5 18:12:00 EDT 2012

If I start Python in interactive mode,
and I yype the commands,
'a=3', 'a', 'print a'
Then the output would look like:
 >>> a = 3
 >>> a
3
 >>> print a
3
Now within an application I'd like to achieve exactly this behaviour
Meaning, that
- for assignments nothing is displayed
- for expressions the result of the exprission displayed
- and statements like print statements would be executed
The only thing, that I came up with is following code and that would
even print out results for 'a=3', where the normal interactive python 
would not echo any result.
for cmd in [ 'a=3', 'a', 'print a' ] :
 try:
 print('>>> ' + cmd)
 exec('__rslt = ' + cmd)
 if __rslt is not None:
 print repr(__rslt)
 except SyntaxError:
 exec(cmd)
The result would look like:
 >>> a=3
3
 >>> a
3
 >>> print a
3
 >>>
Is There anything better?