class FIFO
	declare contents

	// define constructors for FIFO objects
	def FIFO()
		this.contents = {}
	end
	def FIFO(contents)
		this.contents = contents
	end

	// define methods for this class
	def push(value)
		contents.append(value)
	end
	def pop()
		if !this.empty()
			value = contents[len(contents) - 1]
			contents.remove(len(contents) - 1)
			return value
		else
			// we could throw our own exception here but
			// we'll return null instead
			return null
		end
	end
	def length()
		return len(contents)
	end
	def extend(itemlist)
		contents += itemlist
	end
	def empty()
		return len(contents) = 0
	end

	// define operators for this class
	def toString()
		return str(contents)
	end
	def operator+(other)
		return this.contents + other.contents
	end
	def operator*(n)
		return this.contents * n
	end
	def operator=(other)
		return this.contents = other.contents
	end
end