def METHOD_NAME(self):
    pk = self.instance.pk if self.instance and self.instance.pk else -1
    geom = self.cleaned_data['geom']
    if geom is None:
        raise forms.ValidationError(_("Invalid snapped geometry."))
    if not geom.simple:
        raise forms.ValidationError(_("Geometry is not simple."))
    if not Path.check_path_not_overlap(geom, pk):
        raise forms.ValidationError(_("Geometry overlaps another."))
    if not geom.valid:
        raise forms.ValidationError(_("Geometry is not valid."))
    return geom