old_contents: from __future__ import absolute_import
  
  from .base import BaseMessage
  from .types import Types
  from .. import rw
  from . import common
  
  
  class CallRequestMessage(BaseMessage):
      """Initiate an RPC call."""
      message_type = Types.CALL_REQ
  
      __slots__ = (
          'flags',
          'ttl',
          'tracing',
  
          'service',
          'headers',
  
          'checksum',
  
          'arg_1',
          'arg_2',
          'arg_3',
      )
  
      def __init__(
          self,
          flags=0,
          ttl=10,
          tracing=None,
          service=None,
          headers=None,
          checksum=None,
          arg_1=None,
          arg_2=None,
          arg_3=None,
      ):
          self.flags = flags
          self.ttl = ttl
          self.tracing = tracing or common.Tracing(0, 0, 0, 0)
          self.service = service or ''
          self.headers = dict(headers) if headers else {"as":"http"}
          if checksum is not None:
              checksum = common.ChecksumType.standardize(checksum)
          self.checksum = checksum or \
              (common.ChecksumType.none, None)
  
          self.arg_1 = arg_1 or ''
          self.arg_2 = arg_2 or ''
          self.arg_3 = arg_3 or ''
  
  
  call_req_rw = rw.instance(
      CallRequestMessage,
      ("flags", rw.number(1)),    # flags:1
      ("ttl", rw.number(4)),      # ttl:4
  
      ("tracing", common.tracing_rw),     # tracing:24
                                          # traceflags: 1
  
      ("service", rw.len_prefixed_string(rw.number(1))),  # service~1
      ("headers", rw.headers(             # nh:1 (hk~1 hv~1){nh}
          rw.number(1),
          rw.len_prefixed_string(rw.number(1))
      )),
  
      ("checksum", common.checksum_rw),   # csumtype:1 (csum:4){0, 1}
  
      ("arg_1", rw.len_prefixed_string(rw.number(2), is_binary=True)),  # arg1~2
      ("arg_2", rw.len_prefixed_string(rw.number(2), is_binary=True)),  # arg2~2
      ("arg_3", rw.len_prefixed_string(rw.number(2), is_binary=True)),  # arg3~2
  )
  
new_contents: from __future__ import absolute_import
  
  from .base import BaseMessage
  from .types import Types
  from .. import rw
  from . import common
  
  
  class CallRequestMessage(BaseMessage):
      """Initiate an RPC call."""
      message_type = Types.CALL_REQ
  
      __slots__ = (
          'flags',
          'ttl',
          'tracing',
  
          'service',
          'headers',
  
          'checksum',
  
          'arg_1',
          'arg_2',
          'arg_3',
      )
  
      def __init__(
          self,
          flags=0,
          ttl=10,
          tracing=None,
          service=None,
          headers=None,
          checksum=None,
          arg_1=None,
          arg_2=None,
          arg_3=None,
      ):
          self.flags = flags
          self.ttl = ttl
          self.tracing = tracing or common.Tracing(0, 0, 0, 0)
          self.service = service or ''
          self.headers = dict(headers) if headers else {}
          if checksum is not None:
              checksum = common.ChecksumType.standardize(checksum)
          self.checksum = checksum or \
              (common.ChecksumType.none, None)
  
          self.arg_1 = arg_1 or ''
          self.arg_2 = arg_2 or ''
          self.arg_3 = arg_3 or ''
  
  
  call_req_rw = rw.instance(
      CallRequestMessage,
      ("flags", rw.number(1)),    # flags:1
      ("ttl", rw.number(4)),      # ttl:4
  
      ("tracing", common.tracing_rw),     # tracing:24
                                          # traceflags: 1
  
      ("service", rw.len_prefixed_string(rw.number(1))),  # service~1
      ("headers", rw.headers(             # nh:1 (hk~1 hv~1){nh}
          rw.number(1),
          rw.len_prefixed_string(rw.number(1))
      )),
  
      ("checksum", common.checksum_rw),   # csumtype:1 (csum:4){0, 1}
  
      ("arg_1", rw.len_prefixed_string(rw.number(2), is_binary=True)),  # arg1~2
      ("arg_2", rw.len_prefixed_string(rw.number(2), is_binary=True)),  # arg2~2
      ("arg_3", rw.len_prefixed_string(rw.number(2), is_binary=True)),  # arg3~2
  )
  
subject: remove test code