::= | | | | | | | | | ::= ".set(" ")" ";" ::= "if" "(" ")" "{" * "}" ["else" "{" * "}"]? ::= "while" "(" ")" "{" * "}" ::= "loop" "(" "," "->" ["," ]? ")" "{" * "}" ::= "rloop" "(" "," "->" ["," ]? ")" "{" * "}" ::= "(" ? ")" ";" ::= "rtn" ";" ::= "using" ".set(" ")" "{" * "}" ::= ".attempt" "{" * "}" ::= ("ok" | | "error") "{" * "}" ::= ".fail(" ["(" ? ")"]? ")" ";"