In http://www.reinteract.org/trac/ticket/6 Eduardo de Oliveira Padoan said:
A related note: currently, printed and returned values are indistinguishable. When this issue is fixed, one will have no way to say if a value was returned or printed by the called thing.
IPython dont have this problem:
In [1]: 1+1
Out[1]: 2
In [2]: print 1+1
2
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Displaying the two types of output in different colors or styles might be a solution.
I don't see going to the IPython style, since the natural thing to reference old results
in Reinteract is not the cryptic _2, but rather to just go up, edit the line that returned
the result and change it to assign it to a properly named variable.