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

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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?