If your embedded python code calls tkinter library (which is used by a lot of graphic producing libraries, including matplotlib), you might get this error:
<THROW> *%Exception.PythonException <CLASS DOES NOT EXIST> 230 ^^0^DO ##CLASS(User.Test).Test()
<class '_tkinter.TclError'>: Can't find a usable init.tcl in the following directories:
c:/intersystems/irispy/lib/python/lib/tcl8.6
c:/intersystems/irispy/lib/tcl8.6
c:/intersystems/lib/tcl8.6
c:/intersystems/irispy/library
c:/intersystems/library
c:/intersystems/tcl8.6.9/library
c:/tcl8.6..png)
.png)



