def _get_contigs_to_keep(self, filename):
        '''Returns a set of names from file called filename. If filename is None, returns an empty set'''
        if filename is None:
            return set()

        with open(filename) as f:
            return {line.rstrip() for line in f}
def _get_contigs_to_keep ( self , filename ) : if filename is None : return set ( ) with open ( filename ) as f : return { line . rstrip ( ) for line in f }
Returns a set of names from file called filename. If filename is None, returns an empty set