code: def A1(self, algorithm, auth_pass):
          
  
          username = self.params["username"]
          if algorithm == 'MD5' or not algorithm:
              return "%s:%s:%s" % (username, self.realm, auth_pass)
          elif algorithm == 'MD5-Sess':
              return self.apply_checksum('%s:%s:%s:%s:%s' % \
                                         (username,
                                         self.realm,
                                         auth_pass,
                                         self.params['nonce'],
                                         self.params['cnonce']))
docs: If 'algorithm' is "MD5" or unset, A1 is:
           A1 = unq(username-value) ":" unq(realm-value) ":" passwd
  
           if 'algorithm' is 'MD5-Sess', A1 is:
           A1 = H( unq(username-value) ":" unq(realm-value) ":" passwd )
            ":" unq(nonce-value) ":" unq(cnonce-value)