def find_all(conditions)
      conditions = validate_conditions(conditions)

      matches = []
      matches << self if match(conditions)
      @children.each do |child|
        matches.concat child.find_all(conditions)
      end
      matches
    end
def find_all(conditions)
      conditions = validate_conditions(conditions)

      matches = []
      matches << self if match(conditions)
      @children.each do |child|
        matches.concat child.find_all(conditions)
      end
      matches
    end
Search for all nodes that match the given conditions, and return them
 as an array.