alse) If verbose=false, returns a json object with transaction list and mempool sequence number attached.

Result (for verbose = false):
[           (json array)
  "hex",    (string) The transaction id
  ...
]

Result (for verbose = true):
{                                         (json object)
  "transactionid" : {                     (json object)
    "vsize" : n,                          (numeric) virtual transaction size as defined in BIP 141. This is different from actual serialized size for witness tr