ice_cream

class Addressbook	def initialize		@persons = []   #empty array		end	def add(person)		@persons += [person]		@persons.sort { |a,b| by_name(a,b) }		end	def remove(person)		@persons.delete(person) #uses Array#delete method		end			#automatic sorting!	def by_name(a,b)		if a.first_name == b.first_name			a.last_name <=> b.last_name		else			a.first_name <=> b.first_name		end 	end 	 	def to_s 		@persons.each do |elem| 		 	puts elem 		end 	endend