+class AAsNotnullExpr
+special PExpr
+ readable writable attr _n_expr: PExpr = null
+ readable writable attr _n_kwas: TKwas = null
+ readable writable attr _n_kwnot: TKwnot = null
+ readable writable attr _n_kwnull: TKwnull = null
+end
+class AIssetAttrExpr
+special AAttrFormExpr
+ readable writable attr _n_kwisset: TKwisset = null
+end