+| ASTFE_EXPR_AND: ∀t:ast_base_type.
+ astfe_expr e (AST_TYPE_BASE t) → astfe_expr e (AST_TYPE_BASE t) → astfe_expr e (AST_TYPE_BASE t)
+| ASTFE_EXPR_OR: ∀t:ast_base_type.
+ astfe_expr e (AST_TYPE_BASE t) → astfe_expr e (AST_TYPE_BASE t) → astfe_expr e (AST_TYPE_BASE t)
+| ASTFE_EXPR_XOR: ∀t:ast_base_type.
+ astfe_expr e (AST_TYPE_BASE t) → astfe_expr e (AST_TYPE_BASE t) → astfe_expr e (AST_TYPE_BASE t)