Import lots of variables in a single line of code

- "codegen.macro": "^1.0.0",
- node -v: v9.11.1
- yarn -v: 1.3.2

I'm generating variables so that my colleague who doesn't know how to code can write simple code now.

[💖this part has no problem]
```javascript
// ./memeTemplate/variables.js
const codegen = require('codegen.macro');

// preload formulas variables, and generate more variables, so my colleague can import them easily
codegen`
const fs = require('fs');

const formulasJSON = JSON.parse(fs.readFileSync(require.resolve('../formulas.json'), 'utf8'));
const variableNames = [
...Object.keys(formulasJSON),
...Object.keys(formulasJSON).map(name => '上期' + name),
...Object.keys(formulasJSON).map(name => '上上期' + name),
];

module.exports = variableNames
.map(
variableName =>
'export var ' + variableName.replace(/[（）、:()]/g, '') + ' = loader => loader.load("' + variableName + '")'
)
.join(';');
`;

```

[Here are problems]
```js
// ./templates.js
// try to automatiously import variables
codegen`
'const { ' + Object.keys(require('./memeTemplate/variables')).join(',') + '} = require("./memeTemplate/variables");'
`;

// using the automatiously imported variable
`
偿债能力分析
2017年流动资产合计为${流动资产合计}
`
```
Now it will show an error ```./src/templates.js
Module build failed: MacroError: The macro you imported from "undefined" is being executed outside the context of compilation with babel-plugin-macros. This indicates that you don't have the babel plugin "babel-plugin-macros" configured correctly. Please see the documentation for how to configure babel-plugin-macros properly```

I had tried ```console.log(
'const { ' + Object.keys(require('./memeTemplate/variables')).join(',') + '} = require("./memeTemplate/variables");'
);```, it logs the correct require statement:

```js
const { 净资产收益率,平均净资产, ...hugeAmountOfVariables } = require("./memeTemplate/variables");
```

And if I just import them statisticly:
```js
import {
销售利润率,
流动比率,
...lotsToImport,
} from './memeTemplate/variables';
```
It works correctly.

So I can't use codegen to load code generated by codegen?
Or I can't use codegen to generate import statement?

Start with ./templates.js and ./memeTemplate/variables.js, then reproduce the MacroError using the shown codegen.macro examples and the reported Babel setup. Determine whether nested code generation or generated import statements are supported; done means the documented behavior is clear and the example either builds successfully or reports the limitation accurately.

Written by the indexing model from the issue text.