def hostname_or_ip_address(blank = false)
      regexp = Regexp.union(hostname, ip_address)
      add_blank_option(regexp, blank)
    end
def hostname_or_ip_address(blank = false)
      regexp = Regexp.union(hostname, ip_address)
      add_blank_option(regexp, blank)
    end
Creates a regular expression to match a hostname or ip address