code: public boolean getBoolean(int key) {
          Any3<Boolean, Integer, String> value = data.get(Any2.<Integer, String>left(key));
          if (value == null)
              throw new IllegalArgumentException("missing argument for param " + key);
          return value.get1().orElseThrow(() -> new IllegalArgumentException("expected boolean argument for param " + key));
      }
docs: Return the boolean value indicated by the given numeric key.
  
  @param key The key of the value to return.
  @return The boolean value stored under the given key.
  @throws IllegalArgumentException if the value is absent or not a boolean.