function assertArg (arg, name, reason) {
    if (!arg) {
      throw Error('areq', "Argument '{0}' is {1}", (name || '?'), (reason || 'required'));
    }
    return arg;
  }
/**
 * throw error if the argument is falsy.
 */
throw error if the argument is falsy.
throw error if the argument is falsy .
function assertArg (arg, name, reason) {
    if (!arg) {
      throw Error('areq', "Argument '{0}' is {1}", (name || '?'), (reason || 'required'));
    }
    return arg;
  }
function assertArg ( arg , name , reason ) { if ( ! arg ) { throw Error ( 'areq' , "Argument '{0}' is {1}" , ( name || '?' ) , ( reason || 'required' ) ) ; } return arg ; }
throw error if the argument is falsy.
throw error if the argument is falsy .