docs: def compact(self) -> str:
          """
          Return a transaction in its compact format from the instance
  
          :return:
          """
          """TX:VERSION:NB_ISSUERS:NB_INPUTS:NB_UNLOCKS:NB_OUTPUTS:HAS_COMMENT:LOCKTIME
  PUBLIC_KEY:INDEX
  ...
  INDEX:SOURCE:FINGERPRINT:AMOUNT
  ...
  PUBLIC_KEY:AMOUNT
  ...
  COMMENT
  """
          doc = "TX:{0}:{1}:{2}:{3}:{4}:{5}:{6}\n".format(self.version,
                                                          len(self.issuers),
                                                          len(self.inputs),
                                                          len(self.unlocks),
                                                          len(self.outputs),
                                                          '1' if self.comment != "" else '0',
                                                          self.locktime)
          if self.version >= 3:
              doc += "{0}\n".format(self.blockstamp)
  
          for pubkey in self.issuers:
              doc += "{0}\n".format(pubkey)
          for i in self.inputs:
              doc += "{0}\n".format(i.inline(self.version))
          for u in self.unlocks:
              doc += "{0}\n".format(u.inline())
          for o in self.outputs:
              doc += "{0}\n".format(o.inline())
          if self.comment != "":
              doc += "{0}\n".format(self.comment)
          for s in self.signatures:
              doc += "{0}\n".format(s)
  
          return doc