docs: def summary(self):
          """Return a string summary of transaction"""
          return "\n".join([
              "Transaction:",
              "  When:        " + self.date.strftime("%a %d %b %Y"),
              "  Description: " + self.desc.replace('\n', ' '),
              "  For amount:  {}".format(self.amount),
              "  From:        {}".format(
                  ", ".join(map(lambda x: x.account, self.src)) if self.src \
                      else "UNKNOWN"
              ),
              "  To:          {}".format(
                  ", ".join(map(lambda x: x.account, self.dst)) if self.dst \
                      else "UNKNOWN"
              ),
              ""
          ])