docs: def is_flash_encryption_key_valid(self):
  
          """ Bit 0 of efuse_rd_disable[3:0] is mapped to BLOCK1
          this bit is at position 16 in EFUSE_BLK0_RDATA0_REG """
          word0 = self.read_efuse(0)
          rd_disable = (word0 >> 16) & 0x1
  
          # reading of BLOCK1 is NOT ALLOWED so we assume valid key is programmed
          if rd_disable:
              return True
          else:
              """ reading of BLOCK1 is ALLOWED so we will read and verify for non-zero.
              When ESP32 has not generated AES/encryption key in BLOCK1, the contents will be readable and 0.
              If the flash encryption is enabled it is expected to have a valid non-zero key. We break out on
              first occurance of non-zero value """
              key_word = [0] * 7
              for i in range(len(key_word)):
                  key_word[i] = self.read_efuse(14 + i)
                  # key is non-zero so break & return
                  if key_word[i] != 0:
                      return True
              return False