day2.py

#!/bin/python

class Submarine():
  def __init__(self):
    self.horizontal = 0
    self.depth = 0
    self.aim = 0
  def forward(self, amount):
    self.horizontal += amount
    self.depth += amount * self.aim
  def up(self, amount):
    self.aim -= amount
  def down(self, amount):
    self.aim += amount

sub = Submarine()

with open('day2.txt') as f:
  for line in f:
    c, a = line.split()
    getattr(sub, c)(int(a))

print(f'Part Two: {sub.depth * sub.horizontal}')