#NEWLINE# def __init__( self , relations = None , files = None ) : #NEWLINE# #INDENT# 'Constructor for the database class\n        ' #NEWLINE# self . _relations = { #NEWLINE# #INDENT# #NEWLINE# #UNINDENT# } #NEWLINE# if ( not atmost_one ( files , files ) ) : #NEWLINE# #INDENT# raise ValueError ( 'Only one of relations and files should be given' ) #NEWLINE# #UNINDENT# if files : #NEWLINE# #INDENT# relations = self . _initialize_relations ( files ) #NEWLINE# #UNINDENT# if relations : #NEWLINE# #INDENT# for relation in relations : #NEWLINE# #INDENT# self . add_relation ( relation )