def __getitem__(self, key):
        """
        USE THIS IF YOU ARE CONFIDENT THIS IS A MANY-TO-ONE MAPPING
        RETURN THE SINGLE CO-DOMAIN OBJECT THIS key MAPS TO
        """
        output = [v for k, v in self.all if k == key]
        if not output:
            return None
        elif len(output) == 1:
            return output[0]
        else:
            Log.error("Not allowed")
def __getitem__ ( self , key ) : output = [ v for k , v in self . all if k == key ] if not output : return None elif len ( output ) == 1 : return output [ 0 ] else : Log . error ( "Not allowed" )
USE THIS IF YOU ARE CONFIDENT THIS IS A MANY-TO-ONE MAPPING
        RETURN THE SINGLE CO-DOMAIN OBJECT THIS key MAPS TO