srfi-207 (String-notated bytevectors)
setup bytestring 
  --create
      make-bytestring 
  --operations
      bytestring-replace (same to srfi-xxxx interface or extended srfi-xx)
  --transforms
    
  --reader
      read-textual-bytestring (related to srfi-xxx)
      implementation file (module)
  --writer 
      implementation file (module)