'Obtain a list of base filters to apply to an instance.
The return value should be a list of strings, each
specifying a filter name.  Subclasses can override this
function to add additional filters as needed.  Additional
filters added to the list must also be correctly defined
within the subclass.'

def get_base_filter_list(self, instance, allow_dhcp):

    if allow_dhcp:
        base_filter = 'nova-base'
    else:
        base_filter = 'nova-nodhcp'
    return [base_filter]
