docs: def parse_deprecation(self):
          '''Checks to see if the PDB file has been deprecated and, if so, what the new ID is.'''
          deprecation_tag = self.main_tag.getElementsByTagName("PDBx:pdbx_database_PDB_obs_sprCategory")
          assert(len(deprecation_tag) <= 1)
          if deprecation_tag:
              deprecation_tag = deprecation_tag[0]
  
              deprecation_subtag = deprecation_tag.getElementsByTagName("PDBx:pdbx_database_PDB_obs_spr")
              assert(len(deprecation_subtag) == 1)
              deprecation_subtag = deprecation_subtag[0]
              assert(deprecation_subtag.hasAttribute('replace_pdb_id'))
              assert(deprecation_subtag.hasAttribute('pdb_id'))
              old_pdb_id = deprecation_subtag.getAttribute('replace_pdb_id').upper()
              new_pdb_id = deprecation_subtag.getAttribute('pdb_id').upper()
  
              if self.pdb_id == old_pdb_id:
                  self.deprecated = True
                  self.replacement_pdb_id = new_pdb_id
              else:
                  assert(self.pdb_id == new_pdb_id)