Any rule element followed by an asterisk (*) matches zero or more instances of the rule from the input string. The AST result is the vector of the AST results from the matched rule. This will be empty if there are no matches.

Examples
USING: prettyprint peg.ebnf ; "aab" EBNF[[ rule="a"* "b" ]] .
V{ V{ "a" "a" } "b" }

USING: prettyprint peg.ebnf ; "b" EBNF[[ rule="a"* "b" ]] .
V{ V{ } "b" }