def in_range?( val )
      val = val.to_i
      (@above.nil? or val > @above) and
        (@below.nil? or val < @below) and
        (@valid_range.nil? or @valid_range.include?(val))
    end
def in_range?( val )
      val = val.to_i
      (@above.nil? or val > @above) and
        (@below.nil? or val < @below) and
        (@valid_range.nil? or @valid_range.include?(val))
    end
checks field against +valid_range+, +above+ and +below+ , returning +true+ if it passes
 set attributes, +false+ if it fails any one.