message: python3 ify dfuse error prints
diff: @@ -156,12 +156,12 @@ class DfuDevice:
  self.set_address(addr)
  status = self.wait_while_state(DfuState.DFU_DOWNLOAD_BUSY)
  if status[1] != DfuState.DFU_DOWNLOAD_IDLE:
  - raise RuntimeError("An error occured. Device Status: %r" % status)
  + raise RuntimeError("An error occured. Device Status: {!r}".format(status))
  # take device out of DFU_DOWNLOAD_SYNC and into DFU_IDLE
  self.abort()
  status = self.wait_while_state(DfuState.DFU_DOWNLOAD_SYNC)
  if status[1] != DfuState.DFU_IDLE:
  - raise RuntimeError("An error occured. Device Status: %r" % status)
  + raise RuntimeError("An error occured. Device Status: {!r}".format(status))
  def erase_sector(self, sector):
  @@ -169,7 +169,7 @@ class DfuDevice:
  self.erase(sector['addr'])
  status = self.wait_while_state(DfuState.DFU_DOWNLOAD_BUSY, timeout=sector['len']/32)
  if status[1] != DfuState.DFU_DOWNLOAD_IDLE:
  - raise RuntimeError("An error occured. Device Status: %r" % status)
  + raise RuntimeError("An error occured. Device Status: {!r}".format(status))
  def write_sector(self, sector, data):
  self.set_alternate_safe(sector['alt'])
  @@ -184,7 +184,7 @@ class DfuDevice:
  self.write(blocknum, block)
  status = self.wait_while_state(DfuState.DFU_DOWNLOAD_BUSY)
  if status[1] != DfuState.DFU_DOWNLOAD_IDLE:
  - raise RuntimeError("An error occured. Device Status: %r" % status)
  + raise RuntimeError("An error occured. Device Status: {!r}".format(status))
  def read_sector(self, sector):
  """
  