#NEWLINE# def check_client_key( self , client_key ) : #NEWLINE# #INDENT# 'Check that the client key only contains safe characters\n        and is no shorter than lower and no longer than upper.\n        ' #NEWLINE# ( lower , upper ) = self . client_key_length #NEWLINE# return ( ( set ( client_key ) <= self . safe_characters ) and ( lower <= len ( client_key ) <= upper ) )