Error on Jason's code : Line 24 : issue with inject.

class BankAccount
    attr_reader :transactions
    include Enumerable

    def <=> (other_account)
        self.balance <=> other_account.balance
    end

    def initialize(name)
        @name = name
        @balance = balance
        @transactions = []
    end

    def deposit(amount)
        @transactions.push(amount)
    end

    def withdraw(amount)
        @transactions.push(-amount)
    end

    def balance
        @transactions.inject(0) { |sum, iterator| sum += iterator }
    end

    def each
        @transactions.each{|transaction| yield transaction}
    end
end

account1 = BankAccount.new("John Stoveld")
account1.deposit(100)
account1.withdraw(50)
account1.deposit(500)
account1.withdraw(21)

account1.each do |transaction|
    puts transaction
end