def _containerSetPath(container, folderpath, specfiles):
    """Helper function for :class:`MsrunContainer`, :class:`SiiContainer` and
    :class:`FiContainer`. Changes the folderpath of the specified specfiles in
    container.info: ``container.info[specfile]['path'] = folderpath``.

    :param container: a container like class that has an attribute ``.info``
    :param folderpath: a filedirectory
    :param specfiles: a list of ms-run names
    """
    if not os.path.exists(folderpath):
        warntext = 'Error while calling "_containerSetPath()": The specified '\
                   'directory "%s" does not exist!' %(folderpath, )
        warnings.warn(warntext)
    for specfile in specfiles:
        if specfile in container.info:
            container.info[specfile]['path'] = folderpath
        else:
            warntext = 'Error while calling "_containerSetPath()": The '\
                       'specfile "%s" is not present in the container!'\
                       %(specfile, )
            warnings.warn(warntext)