[Exim] condition syntax question

So, I have this value:
domainlist local_domains = @ : @[] : localhost : MAILNAME : LISTDOMAIN : CONFDIR/domains/localdomains : CONFDIR/domains/localdomains_norewrite

And I'd like to have an ACL test against it:

# Forged HELOs
  deny    message       = Forged hostname detected in HELO - $sender_helo_name
          hosts         = !+relay_from_hosts
          log_message   = Forged hostname detected in HELO - $sender_helo_name
          condition     = ${lookup {$sender_helo_name} +local_domains}{yes}{no}}

Of course, the last line is invalid, but I just wrote it to show what I'm
trying to do

Any suggestions?

Thanks
Marc
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