the user to think to the correct interface when the subroutine is called.
A flag is called as</p>
<p>In python I need to look at code or docstring to understand if a value is modified and this can also not be consistent (some method can work as functions, others as procedures.
self.data=newdata makes a method a procedure, self.copy().data=newdata; return res is a function</p>
<dl class="py exception">
<dt class="sig sig-object py" id="pySurf.data2D.EmptyPlotRangeWarning">
<em class="property"><span class="p