Here is objectscript package template, which has an example module.xml with almost everything which could happen in a package.

Take a look on invoke tag:

      <Invokes>
        <Invoke Class="community.objectscript.PersistentClass" Method="CreateRecord"></Invoke>
        <Invoke Class="community.objectscript.ClassExample" Method="SetToTheGlobal">
          <Arg>42</Arg>
          <Arg>Text Data</Arg>
        </Invoke>
      </Invokes>

Place calls elements <Invoke>  in <Invokes> tag. You can pass parameters if you need.

Hi Adel!

Maybe it's not the answer to how to call the procedure from Python. But as soon as you have some ObjectScript code already you may want to try the way to call Python (pandas) from IRIS using Objectscript and transfer the data from your query to the python libraries and run it.

Python Gateway does the thing, here is the set of articles and also tagging @Eduard Lebedyuk and @Sergey Lukyanchikov to provide more details if any.