| " " ([~]*) "\n"
any !::= [~]*
-s ::= !any "\n\n" !ww statement !ww "\n\n" !any => smt
-ww ::= sp*
+s ::= any "\n\n" ww statement ww "\n\n" any => smt
+ww !::= sp*
ws !::= sp**
sp ::= " "
-block ::= "\n" !indent blockBody
+block ::= "\n" indent blockBody
&~ "\n" outdent [~\ ] [~]*
blockBody ::= statement