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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 get_residue_annotations(self, start_resnum, end_resnum=None):
 """Retrieve letter annotations for a residue or a range of residues Args: start_resnum (int):
 Residue number end_resnum (int):
 Optional residue number, specify if a range is desired Returns: dict: Letter annotations for this residue or residues """

        if not end_resnum:
            end_resnum = start_resnum

        # Create a new SeqFeature
        f = SeqFeature(FeatureLocation(start_resnum - 1, end_resnum))

        # Get sequence properties
        return f.extract(self).letter_annotations