Demo of issue with creating babel plugin to dynamically insert `import` declaration. See babel/babel#1777

demo.js

var
  babel = require('babel'),
  output;

function plugin (babel) {
  var t = babel.types;
  var transformers = {
    Program: {
      enter: function (node) {
        var newImport = t.importDeclaration(
          [t.importDefaultSpecifier(t.identifier("x"))],
          t.literal("x")
        );

        this.unshiftContainer('body', newImport);
      }
    }
  };

  return new babel.Transformer('plugin', transformers);
}
// plugin

output = babel.transform(
  "x();",
  {
    plugins: [plugin],
  }
).code;

console.log(output);

console.log("****************************************");

output = babel.transform(
  "import x from 'x'; x();",
  {
  }
).code;

console.log(output);