code: def force_bytes(s, encoding='utf-8', strings_only=False, errors='strict'):
      
      if isinstance(s, memoryview):
          s = bytes(s)
      if isinstance(s, bytes):
          if encoding == 'utf-8':
              return s
          else:
              return s.decode('utf-8', errors).encode(encoding, errors)
      if strings_only and (s is None or isinstance(s, int)):
          return s
      if not isinstance(s, six.string_types):
          try:
              if six.PY3:
                  return six.text_type(s).encode(encoding)
              else:
                  return bytes(s)
          except UnicodeEncodeError:
              if isinstance(s, Exception):
                  # An Exception subclass containing non-ASCII data that doesn't
                  # know how to print itself properly. We shouldn't raise a
                  # further exception.
                  return b' '.join([force_bytes(arg, encoding, strings_only,
                                                errors) for arg in s])
              return six.text_type(s).encode(encoding, errors)
      else:
          return s.encode(encoding, errors)
docs: Similar to smart_bytes, except that lazy instances are resolved to
      strings, rather than kept as lazy objects.
  
      If strings_only is True, don't convert (some) non-string-like objects.