makushline

class GPSCoordinate
    attr_reader :latitude, :longitude
    def initialize(latitude, longitude)
        @latitude  = latitude
        @longitude = longitude
    end
end

makushline

def flatten(input)
    raise ArgumentError.new("Only arrays are allowed") if !input.is_a?(Array)
    output = []
    input.each do |element|
        if element.is_a?(Array)
            output += flatten(element)
        else
            output << element
        end
    end