# $user_by_uid{$uid}->{$host}
$var= $user_by_uid{$uid}
$key= $host

##</code><code>##

sub my_exists {
  my ($hash_ref,$key)= @_;
  return $hash_ref and exists $hash_ref->{$key}
}

##</code><code>##

sub my_fake_exists {
  my ($hash_ref,$key)=@_;
  $hash_ref={} if not defined $hash_ref; #fake autoviv
  return exists $hash_ref->{$key}; # do the lookup
}