STATEMENT = CONDITION | OPERATION | SUBTREE
OPERATION = WS VARNAME WS ( '=' | '+=' ) WS EXPRESSION
-SUBTREE = WS VARNAME WS '{' BLOCK '}'
+SUBTREE = WS VARNAME WS '{' BLOCK WS '}'
CONDITION = WS 'if' FORMULA WS '{' BLOCK WS '}'
FORMULA = WS (( EXPRESSION WS ( '!=' | '==' ) WS EXPRESSION ) | '(' AND WS ')' | '(' OR WS ')' | NOT )