def make_valid_roles *roles      
      roles = roles.to_symbols_uniq
      return [] if roles.empty?                
      check_valid_roles? roles.map{|r| r.to_s.alpha_numeric}
    end
def make_valid_roles *roles      
      roles = roles.to_symbols_uniq
      return [] if roles.empty?                
      check_valid_roles? roles.map{|r| r.to_s.alpha_numeric}
    end
Ensures the role are valid
 @param [Symbol] list of roles
 @return [Array<Symbol>] the valid roles from the list of roles given