def merge(other)
      @selector.update(other.selector)
      @options.update(other.options)
      @documents = other.documents
    end
def merge(other)
      @selector.update(other.selector)
      @options.update(other.options)
      @documents = other.documents
    end
Create the new +Criteria+ object. This will initialize the selector
 and options hashes, as well as the type of criteria.

 Options:

 type: One of :all, :first:, or :last
 klass: The class to execute on.
 Merges another object into this +Criteria+. The other object may be a
 +Criteria+ or a +Hash+. This is used to combine multiple scopes together,
 where a chained scope situation may be desired.

 Options:

 other: The +Criteria+ or +Hash+ to merge with.

 Example:

 <tt>criteria.merge({ :conditions => { :title => "Sir" } })</tt>