Fixed #18645 -- Clarified filesizeformat implementation

    filesize_number_format = lambda value: formats.number_format(round(value, 1), 1)

    if bytes < 1024:

    KB = 1<<10

    MB = 1<<20

    GB = 1<<30

    TB = 1<<40

    PB = 1<<50

    if bytes < KB:

        return ungettext("%(size)d byte", "%(size)d bytes", bytes) % {'size': bytes}

    if bytes < 1024 * 1024:

        return ugettext("%s KB") % filesize_number_format(bytes / 1024)

    if bytes < 1024 * 1024 * 1024:

        return ugettext("%s MB") % filesize_number_format(bytes / (1024 * 1024))

    if bytes < 1024 * 1024 * 1024 * 1024:

        return ugettext("%s GB") % filesize_number_format(bytes / (1024 * 1024 * 1024))

    if bytes < 1024 * 1024 * 1024 * 1024 * 1024:

        return ugettext("%s TB") % filesize_number_format(bytes / (1024 * 1024 * 1024 * 1024))

    return ugettext("%s PB") % filesize_number_format(bytes / (1024 * 1024 * 1024 * 1024 * 1024))

    if bytes < MB:

        return ugettext("%s KB") % filesize_number_format(bytes / KB)

    if bytes < GB:

        return ugettext("%s MB") % filesize_number_format(bytes / MB)

    if bytes < TB:

        return ugettext("%s GB") % filesize_number_format(bytes / GB)

    if bytes < PB:

        return ugettext("%s TB") % filesize_number_format(bytes / TB)

    return ugettext("%s PB") % filesize_number_format(bytes / PB)

@register.filter(is_safe=False)

def pluralize(value, arg='s'):