It should return the contents of the page as an array of one or more items to print. This optional parameter points to a reference to the subroutine responsible for drawing the last page of the series. This optional parameter indicates the content type of each page. Normally the module assumes that each page is of a homogenous MIME type. This indicates the delay, in seconds, between frames.
Smaller delays refresh the page faster.
Fractional values are allowed. If you use this option, you will be responsible for producing the HTTP header for each page. The delay may be fractional. Users of other servers should see their documentation for help. Copyright 1995-1998, Lincoln D. Stein.