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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 _coerce_target(self, target):
 """ Internal method to coerce a target to a string. The assumption is that if it is not ``None`` and not a string, it is a Django ``FieldFile`` object. """

        if not target or isinstance(target, six.string_types):
            return target
        if not hasattr(target, 'instance'):
            return None

        if getattr(target.instance, '_deferred', False):
            model = target.instance._meta.proxy_for_model
        else:
            model = target.instance.__class__

        return '%s.%s.%s' % (
            model._meta.app_label,
            model.__name__,
            target.field.name,
        )