code: private void initSymbolBefore(Node n) {
      compiler.ensureLibraryInjected("es6/symbol", false);
      Node statement = NodeUtil.getEnclosingStatement(n);
      Node initSymbol = IR.exprResult(IR.call(NodeUtil.newQName(compiler, "$jscomp.initSymbol")));
      statement.getParent().addChildBefore(initSymbol.useSourceInfoFromForTree(statement), statement);
      compiler.reportChangeToEnclosingScope(initSymbol);
    }
docs: Inserts a call to $jscomp.initSymbol() before {@code n}.