if I have a Mixin class A_Mixin(metaclass=DeclarativeColumnMetaclass) pass and a table class class B_table(A_Mixin, tables.Table): pass I get the typeError:metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of athe metaclasses of all its bases. My goal with this approach was to create a mixin to reuse throughout the app for table definition.