Calling task in another xml file from main build file

[Z W]

Hi

I have multiple tasks and I like to move a few tasks into another xml file.
What's the syntax to call another task in another xml file from the original
buildfile ?
Eg:


<ant antfile="task_file.xml">

<!-- how do I make a task call ? -->

</ant>



task_file.xml

<project>

<target name="test_hi">

<echo message="hi" />

</target>

</project>



Any example similar to this is appreciated also.

Thanks