def parse_file(file_path)
      node = parse_xml(file_path)
      node.xpath('*').each do |node_child|
        case node_child.name
        when 'Relationships'
          parse(node_child)
        end
      end
      self
    end
def parse_file(file_path)
      node = parse_xml(file_path)
      node.xpath('*').each do |node_child|
        case node_child.name
        when 'Relationships'
          parse(node_child)
        end
      end
      self
    end
Parse .rels file
 @param file_path [String] path to file
 @return [Relationships]