def getFeature(self, prop):
        """Return the feature with that name."""

        f = self.props.get(prop, None)
        if not f:
            return None
        if isinstance(f, Feature):
            return f
        if isinstance(f, tuple):
            if f[0]:
                return f[0]
            elif f[1]:
                return f[1]
            raise Exception("Getting value from a property with a constrain")
        if isinstance(f, list):
            return f
        raise Exception("Getting value from a not simple property.")
Return the feature with that name.