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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def to_uint(self):
 """Convert vector to an unsigned integer, if possible. This is only useful for arrays filled with zero/one entries. """

        num = 0
        for i, f in enumerate(self._items):
            if f.is_zero():
                pass
            elif f.is_one():
                num += 1 << i
            else:
                fstr = "expected all functions to be a constant (0 or 1) form"
                raise ValueError(fstr)
        return num