/extensions/flyrb/lib/flyrb/hash_math.rb

 1class Hash
 2  alias :+ :merge
 3  def -(thing_to_be_deleted)
 4    if thing_to_be_deleted.is_a? Hash
 5      thing_to_be_deleted.each do |key, value|
 6        self.delete(key) if self[key] == value
 7      end
 8    elsif self.keys.include? thing_to_be_deleted
 9      self.delete(thing_to_be_deleted)
10    end
11    self
12  end
13end