Port Palermo

Solution

module Port
  IDENTIFIER = :PALE

  def self.get_identifier(city)
    city[0..3].upcase.to_sym
  end

  def self.get_terminal(ship_identifier)
    (1)
    ship_identifier.to_s.match(/^(OIL|GAS)/) ? :A : :B
  end
end
1 Could be replaced with something like this: 
>> ship = 'GAS123'
=> "GAS123"
>> %w[OIL GAS].member?(ship[0..2].upcase)
=> true