import java.util.HashMap;
import java.util.Objects;

public class Arguments {
  private final HashMap<String,String> map = new HashMap<>();

  void put(String name, String value) {
    map.put(name, value);
  }

  public String getValue(String name) {
    Objects.requireNonNull(name);
    String value = map.get(name);
    if (value == null) {
      throw new IllegalArgumentException("unknown value " + name);
    }
    return value;
  }
}