The following is a list of common questions asked about pyOpenMS.
Add an entry to src/pyOpenMS/pxds/CLASS_NAME.pxd with the signature of your new method(s).
Create a new file src/pyOpenMS/pxds/CLASS_NAME.pxd and use the procedure outlined.
Python does not support passing primitive types (int, double, etc.) by reference, therefore void calculate(double &) will not work.