/*
Suppose the string "yak" is unlucky. Given a string, return a version where all the "yak" are removed, but the "a" can be any char. The "yak" strings will not overlap.
eg:
stringYak("yakpak") → "pak"
stringYak("pakyak") → "pak"
stringYak("yak123ya") → "123ya"
*/
public String stringYak(String str) {
return str.replace("yak","");
}