docs: def compute_tls13_next_traffic_secrets(self):
          """
          Ciphers key and IV are updated accordingly.
          """
          hkdf = self.prcs.hkdf
          hl = hkdf.hash.digest_size
  
          cts = self.tls13_derived_secrets["client_traffic_secrets"]
          ctsN = cts[-1]
          ctsN_1 = hkdf.expand_label(ctsN, "application traffic secret", "", hl)
          cts.append(ctsN_1)
  
          stsN_1 = hkdf.expand_label(ctsN, "application traffic secret", "", hl)
          cts.append(stsN_1)
  
          if self.connection_end == "server":
              self.prcs.tls13_derive_keys(ctsN_1)
              self.pwcs.tls13_derive_keys(stsN_1)
          elif self.connection_end == "client":
              self.pwcs.tls13_derive_keys(ctsN_1)
              self.prcs.tls13_derive_keys(stsN_1)