# A bank to deposit all you have, but with the lack of withdrawal - what a pity.
class Bank
  attr :tresor
  attr :name
  attr :unit

  # ctor.
  # [name] name of the bank
  # [unit] what is this tresor good for.
  def initialize(name, unit)
    @tresor = 0
    @name = name
    @unit = unit
  end
  
  # To deposit some units.
  # [amount] amount as Fixnum
  def deposit(amount)
    raise if amount<0
    @tresor += amount
    puts "    #{amount} #{@unit}'s deposited. #{@name} has now #{@tresor} #{@unit}'s." 
  end

  # A collective deposition. A list of amounts is deposited in one slide.
  # [amounts] an array of amounts
  def collective_deposit(amounts)
    amounts.each { |amount|
      deposit(amount)
    }
  end
end