import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class ForEach {
    void m1() {
        Set<? extends CharSequence> s = new HashSet<CharSequence>();
        for (CharSequence cs : s) {
            cs.toString();
        }
    }

    void m2() {
        Set<CharSequence> s = new HashSet<>();
        for (CharSequence cs : s) {
            cs.toString();
        }
    }

    <T extends Object> void m3(T p) {
        Set<T> s = new HashSet<>();
        for (T cs : s) {
            cs.toString();
        }
    }

    <T extends Object> void m4(T p) {
        Set<T> s = new HashSet<>();
        for (Object cs : s) {
            cs.toString();
        }
    }

    public static <T extends Object> List<T> removeDuplicates(List<T> l) {
        // There are shorter solutions that do not maintain order.
        HashSet<T> hs = new HashSet<>(l.size());
        List<T> result = new ArrayList<>();
        for (T t : l) {
            if (hs.add(t)) {
                result.add(t);
            }
        }
        return result;
    }
}
