Error in `da/examples/dscrash/spec.da`

[jmnotin]

This is related to issue #10 .

In the example DistAlgo program dscrash/spec.da, the comprehensions are written using variable name v that is a state variable bounded in setup. For example, the following line:

V |= setof(v, received(('Value', V2, _)), v in V2)

is compiled as:

self._state.V |= {self._state.v for (_, _, (_ConstantPattern272_, V2, _)) in self._PReceivedEvent_2 if (_ConstantPattern272_ == 'Value') for self._state.v in V2}

Note that in this particular example, it is harmless. Nevertheless, limiting the scope of the variables bounded in comprehensions and existentials, as suggested in #10, could be a good idea.