# File lib/rule_engine.rb, line 88
  def begin_rules
    # if it is true or :finished, see end_rules & method_added
    if @__drp__defining_rules 
      raise DRPError, 'begin rules may only be called once'
    else
      @__drp__rules = {}
      @__drp__defining_rules = true
      @__drp__weights = []
      @__drp__max__depths = []
      # NB max_depth should come first here in case user changes
      # the default to some weight which needs to know the max_depth
      max_depth DEFAULT[:max_depth]
      weight DEFAULT[:weight]
    end
  end