docs: function saveModelSync (modelName, modelMetadata, modelDir) {
    const buffer = `const Arrow = require('arrow')
  var Model = Arrow.Model.extend('${modelName}', ${JSON.stringify(modelMetadata, null, '\t')})
  module.exports = Model`
    fs.writeFileSync(path.join(modelDir, modelMetadata.name.toLowerCase() + '.js'), buffer)
  }