code: def _resolve_file(attributes, input_file, input_identifier, input_reference):
      
      if input_file['isArray']:
          raise InvalidInputReference('Input References to Arrays of input files are currently not supported.\n'
                                      '"{}" is an array of files and can not be resolved for input references:'
                                      '\n{}'.format(input_identifier, input_reference))
      single_file = input_file['files'][0]
  
      try:
          return _get_dict_element(single_file, attributes)
      except KeyError:
          raise InvalidInputReference('Could not get attributes "{}" from input file "{}", needed in input reference:'
                                      '\n{}'.format(attributes, input_identifier, input_reference))
docs: Returns the attributes in demand of the input file.
  
      :param attributes: A list of attributes to get from the input_file.
      :param input_file: The file from which to get the attributes.
      :param input_identifier: The input identifier of the given file.
      :param input_reference: The reference string
      :return: The attribute in demand