class ActiveRecord::Associations::CollectionProxy

def find(*args)

# ]
# #
# #,
# => [
person.pets.find(2, 3)

# => #
person.pets.find(2) { |pet| pet.name.downcase! }

person.pets.find(4) # => ActiveRecord::RecordNotFound: Couldn't find Pet with 'id'=4
person.pets.find(1) # => #

# ]
# #
# #,
# #,
# => [
person.pets

end
has_many :pets
class Person < ActiveRecord::Base

error if the object cannot be found.
rules as ActiveRecord::Base.find. Returns ActiveRecord::RecordNotFound
Finds an object in the collection responding to the +id+. Uses the same 
def find(*args)
  return super if block_given?
  @association.find(*args)
end