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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _ConvertMessageDescriptor(self, desc_proto, package=None, file_desc=None, scope=None, syntax=None):
 """Adds the proto to the pool in the specified package. Args: desc_proto: The descriptor_pb2.DescriptorProto protobuf message. package: The package the proto should be located in. file_desc: The file containing this message. scope: Dict mapping short and full symbols to message and enum types. syntax: string indicating syntax of the file ("proto2" or "proto3") Returns: The added descriptor. """


    if package:
      desc_name = '.'.join((package, desc_proto.name))
    else:
      desc_name = desc_proto.name

    if file_desc is None:
      file_name = None
    else:
      file_name = file_desc.name

    if scope is None:
      scope = {}

    nested = [
        self._ConvertMessageDescriptor(
            nested, desc_name, file_desc, scope, syntax)
        for nested in desc_proto.nested_type]
    enums = [
        self._ConvertEnumDescriptor(enum, desc_name, file_desc, None, scope)
        for enum in desc_proto.enum_type]
    fields = [self._MakeFieldDescriptor(field, desc_name, index)
              for index, field in enumerate(desc_proto.field)]
    extensions = [
        self._MakeFieldDescriptor(extension, desc_name, index,
                                  is_extension=True)
        for index, extension in enumerate(desc_proto.extension)]
    oneofs = [
        descriptor.OneofDescriptor(desc.name, '.'.join((desc_name, desc.name)),
                                   index, None, [], desc.options)
        for index, desc in enumerate(desc_proto.oneof_decl)]
    extension_ranges = [(r.start, r.end) for r in desc_proto.extension_range]
    if extension_ranges:
      is_extendable = True
    else:
      is_extendable = False
    desc = descriptor.Descriptor(
        name=desc_proto.name,
        full_name=desc_name,
        filename=file_name,
        containing_type=None,
        fields=fields,
        oneofs=oneofs,
        nested_types=nested,
        enum_types=enums,
        extensions=extensions,
        options=_OptionsOrNone(desc_proto),
        is_extendable=is_extendable,
        extension_ranges=extension_ranges,
        file=file_desc,
        serialized_start=None,
        serialized_end=None,
        syntax=syntax)
    for nested in desc.nested_types:
      nested.containing_type = desc
    for enum in desc.enum_types:
      enum.containing_type = desc
    for field_index, field_desc in enumerate(desc_proto.field):
      if field_desc.HasField('oneof_index'):
        oneof_index = field_desc.oneof_index
        oneofs[oneof_index].fields.append(fields[field_index])
        fields[field_index].containing_oneof = oneofs[oneof_index]

    scope[_PrefixWithDot(desc_name)] = desc
    self._descriptors[desc_name] = desc
    return desc