empty pipes

[Ray Andrews <rayandrews@xxxxxxxxxxx>]

Is there some way of asking zsh to ignore an empty pipe?  I attempted 
something like this:

print $string | $filter | $another_filter

... and it won't accept the filter being empty but sometimes I want the 
filtering and sometimes not.  There's other ways to do it of course, but 
the above would be cool it it could be made to work.