mintime" : xxx,                         (numeric) The minimum timestamp appropriate for the next block time, expressed in UNIX epoch time
  "mutable" : [                            (json array) list of ways the block template may be changed
    "str",                                 (string) A way the block template may be changed, e.g. 'time', 'transactions', 'prevblock'
    ...
  ],
  "noncerange" : "hex",                    (string) A range of valid nonces
  "sigoplimit" : n,                        (nume