Availability:built-in
string_bytes(?String, 
?Bytes, +Encoding)True when the (Unicode) String is represented by Bytes 
in
Encoding. If String is instantiated it may 
represent text as an atom, string, list of character codes or list or 
characters.
Bytes is always a list of integers in the range 0 ... 
255. At least one of String or Bytes must be 
instantiated. This predicate is notably intended as an intermediate step 
to perform byte oriented operations on text. Examples are (base64) 
encoding, encryption, computing a (secure) hash, etc. Encoding 
is typically
utf8. All valid stream encodings except for wchar_t 
are supported. See section 
2.18.1. Note that this translation is only provided for strings. 
Creating an atom from bytes requires
atom_string/2.172Strings 
are an efficient intermediate and this conversion is needed only in some 
uncommon scenarios.