sub op_expander { shift->_ext_rw(expand_op => @_) }
sub renderer { shift->_ext_rw(render => @_) }
sub op_renderer { shift->_ext_rw(expand_op => @_) }
-sub clause_expander { shift->_ext_rw(expand_cluse => @_) }
+sub clause_expander { shift->_ext_rw(expand_clause => @_) }
sub clause_renderer { shift->_ext_rw(render_clause => @_) }
sub clauses_of {