While following DigitalOcean’s “How To Install the Apache Web Server on Ubuntu 16.04” guide:

Step 1: Install Apache – success :)

sudo apt-get update
sudo apt-get install apache2

Step 2: Adjust the Firewall – failure :(

$ sudo ufw allow 'Apache Full'

returns

ERROR: Need 'to' or 'from' clause

I am a newb. What am I doing wrong?