feat: Python iterators

[fabiomadge]

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[fabiomadge]

No changes to the tests, as they use %testDafnyForEachCompiler.

class Iter:
    def  __init__(self, X):
        self.X = X
        self.a: _dafny.Array = _dafny.Array.empty(1)
        self.stop: TypeVar('X') = self.X()
        self.x: TypeVar('X') = self.X()
        self._iter = None
        pass

    def __dafnystr__(self) -> str:
        return "Iter"
    def ctor__(self, a, stop):
        self.a = a
        self.stop = stop
        self._iter = self.TheIterator()
    def MoveNext(self):
        try:
            next(self._iter)
            return True
        except (StopIteration, TypeError) as e:
            return False
    def TheIterator(self):
        _1_i_: int
        _1_i_ = 0
        with _dafny.label("0"):
            while (_1_i_) < (len(((self).a))):
                with _dafny.c_label("0"):
                    if (_dafny.euclidian_modulus(_1_i_, 2)) == (0):
                        (self).x = ((self).a)[_1_i_]
                        yield
                    (self).x = ((self).a)[_1_i_]
                    if ((self).x) == ((self).stop):
                        raise _dafny.Break("0")
                    if (_dafny.euclidian_modulus(_1_i_, 2)) == (1):
                        yield
                    _1_i_ = (_1_i_) + (1)