Q:

How to use a method to populate a Hash in Ruby?

I am working on a challenge that requests I create 2 classes:
Bank
Person

My goal is to be able to have Bank and Person communicate with each other.  I have that working up until I have to manipulate account balances with the methods below. but I am having trouble creating bank accounts to work with the test input code/output that was given at the bottom of the post.
I have decided to initialize an instance of a hash 
@account_balances = {}

My goal is to add a bank account with zero balance to the hash every time I use the Bank class method
open_account(customer)

Can anyone help?  I might be barking up the wrong tree with the Hash idea....but I have tried other ideas and they didn't work properly.  I figure if I can create the Hash to store the individual accounts, I can use the deposit/withdraw methods to manipulate them.
Bank Class

A:

Inside initialize:
@bank = bank
@customers = {}
puts "#{@bank} bank was just created."

And then inside open_account(customer)
@customers[customer] = 0
puts "#{customer.name}, thanks for opening an account at #{@bank}!"

