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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 _ConvertMapFieldValue(self, value, message, field):
 """Convert map field value for a message map field. Args: value: A JSON object to convert the map field value. message: A protocol message to record the converted data. field: The descriptor of the map field to be converted. Raises: ParseError: In case of convert problems. """

    if not isinstance(value, dict):
      raise ParseError(
          'Map field {0} must be in a dict which is {1}.'.format(
              field.name, value))
    key_field = field.message_type.fields_by_name['key']
    value_field = field.message_type.fields_by_name['value']
    for key in value:
      key_value = _ConvertScalarFieldValue(key, key_field, True)
      if value_field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
        self.ConvertMessage(value[key], getattr(
            message, field.name)[key_value])
      else:
        getattr(message, field.name)[key_value] = _ConvertScalarFieldValue(
            value[key], value_field)