def format_pci_addr(pci_addr: str) ->str:
    """Format a PCI address with 0 fill for parts

    :param: pci_addr: unformatted PCI address
    :type: str
    :returns: formatted PCI address
    :rtype: str
    """
    domain, bus, slot_func = pci_addr.split(':')
    slot, func = slot_func.split('.')
    return '{}:{}:{}.{}'.format(domain.zfill(4), bus.zfill(2), slot.zfill(2
        ), func)
