Unable to call the scale() method in Libgdx for android

I've just started learning Libgdx from today by looking at some of the tutorials and find this framework really good, however, I've bumped in a minor problem. I've set up the fonts with the BitmapFont and was trying to use a method to scale the size of the text, however, I cannot find the scale() method. Did I forget to import something ? or pehaps miss something ?

I've imported import com.badlogic.gdx.graphics.g2d.BitmapFont; for the private BitmapFont font; I was able to change the color fo the font by using font.setColor(Color.GREEN); But I'm unable to call some methods to scale the text . Should I import the entire thing ? or should I have added additional libs in the first place ? I've listed all the imports that I have in my activity.

import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.InputProcessor;
import com.badlogic.gdx.graphics.Color;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.g2d.Animation;
import com.badlogic.gdx.graphics.g2d.BitmapFont;
import com.badlogic.gdx.graphics.g2d.Sprite;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.graphics.g2d.TextureAtlas;