whole_func_string: function IsWritableStreamDefaultWriter(x) {
    if (!typeIsObject(x)) {
      return false;
    }
  
    if (!Object.prototype.hasOwnProperty.call(x, '_ownerWritableStream')) {
      return false;
    }
  
    return true;
  }
func_code_string: function IsWritableStreamDefaultWriter(x) {
    if (!typeIsObject(x)) {
      return false;
    }
  
    if (!Object.prototype.hasOwnProperty.call(x, '_ownerWritableStream')) {
      return false;
    }
  
    return true;
  }
func_documentation_string: Abstract operations for the WritableStreamDefaultWriter.