code: def _identity_stmt(self, stmt: Statement, sctx: SchemaContext) -> None:
          
          if not sctx.schema_data.if_features(stmt, sctx.text_mid):
              return
          id = (stmt.argument, sctx.schema_data.namespace(sctx.text_mid))
          adj = sctx.schema_data.identity_adjs.setdefault(id, IdentityAdjacency())
          for bst in stmt.find_all("base"):
              bid = sctx.schema_data.translate_pname(bst.argument, sctx.text_mid)
              adj.bases.add(bid)
              badj = sctx.schema_data.identity_adjs.setdefault(
                  bid, IdentityAdjacency())
              badj.derivs.add(id)
          sctx.schema_data.identity_adjs[id] = adj
docs: Handle identity statement.