@get
Description:
Get the secret data in the Value.
The value is not necessarily null-terminated unless it was created with [ctorValue.new] or a null-terminated string was passed to
      [ctorValue.new_full].
Parameters:
| this | 
           the value  | 
      
| length | 
           the length of the secret  | 
      
Returns:
| 
           the secret data  |