transformImportDeclaration(tree) {
    if (!tree.importClause ||
      (tree.importClause.type === IMPORT_SPECIFIER_SET &&
      tree.importClause.specifiers.length === 0)) {
      return createExpressionStatement(this.transformAny(tree.moduleSpecifier));
    }
    let binding = this.transformAny(tree.importClause);
    let initializer = this.transformAny(tree.moduleSpecifier);
    return createVariableStatement(CONST, binding, initializer);
  }
Transforms imports to use `const` statements
@param tree
@returns {VariableStatement}