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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 add_region_feature(self, start_resnum, end_resnum, feat_type=None, feat_id=None, qualifiers=None):
 """Add a feature to the features list describing a region of the protein sequence. Args: start_resnum (int):
 Start residue number of the protein sequence feature end_resnum (int):
 End residue number of the protein sequence feature feat_type (str, optional):
 Optional description of the feature type (ie. 'binding domain') feat_id (str, optional):
 Optional ID of the feature type (ie. 'TM1') """

        if self.feature_file:
            raise ValueError('Feature file associated with sequence, please remove file association to append '
                             'additional features.')

        if not feat_type:
            feat_type = 'Manually added protein sequence region feature'
        newfeat = SeqFeature(location=FeatureLocation(start_resnum-1, end_resnum),
                             type=feat_type,
                             id=feat_id,
                             qualifiers=qualifiers)

        self.features.append(newfeat)