DataHandle __add__ operators

I am trying to understand the use-cases of the DataHandle __add__ operators, e.g.:

>>> from GaudiKernel.DataHandle import DataHandle
>>> dh1 = DataHandle("dh1")
>>> "ABC"+dh1
DataHandle('ABCdh1','R','unknown_t')

Is this behavior actually used in LHCb? For ATLAS, we would prefer that the result is a str. But in general, maybe such implicit type conversions are to be avoided to begin with? Could someone from LHCb quickly summarize the use-cases on your side? Also, I see that : has a special meaning in the name. What is it?

@nnolte @clemenci @graven