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+# Issues with library(janus)
+
+The library(janus)  allows embedding Python into  Prolog.  The package
+source is in `packages/swipy`.  This directory can also be compiled as
+a Python package to embed SWI-Prolog into Python, providing the Python
+package `janus_swi`.
+
+## Consequences
+
+The library is not used by any of the other system components and is thus
+only necessary if your application requires it.
+
+## Solutions
+
+When building from  source, the library requires  the Python embedding
+libraries.  On Debian Linux systems these are provided by
+
+   sudo  apt-get install python3 libpython3-dev
+
+On MacOS  and Windows the libraries  and header files are  provided as
+part of the Python installer.
+
+@see https://github.com/SWI-Prolog/packages-swipy