postgres 9.5 create function plpthon3u resets connections to server

this is a repost of a message I mistakenly sent to pgslq-novice, although
it is probably a simple question
I believe my issue may be that I don't have the correct python interpreter
on the server's path. I couldn't find
the required version in the documents and determined what I thought was
required by using dependency walker
on the plpython3.dll in postgres lib/.

A pointer to more detailed doc or example would be great. Thanks.

Anyway, here is my issue:

postgresql 9.5 on windows 10, x64.

I have created the extension plpython3u with python 3.3.5 on the server's
path and it appeared to create the extension successfully:

SELECT * FROM pg_available_extensions
WHERE name like '%python%' order by name;

name | default_version | installed_version |
comment

-------------------+-----------------+-------------------+------------------------------------------
-
hstore_plpython2u | 1.0 | | transform
between hstore and plpython2u
hstore_plpython3u | 1.0 | | transform
between hstore and plpython3u
hstore_plpythonu | 1.0 | | transform
between hstore and plpythonu
ltree_plpython2u | 1.0 | | transform
between ltree and plpython2u
ltree_plpython3u | 1.0 | | transform
between ltree and plpython3u
ltree_plpythonu | 1.0 | | transform
between ltree and plpythonu
plpython2u | 1.0 | | PL/Python2U
untrusted procedural language
plpython3u | 1.0 | 1.0 | PL/Python3U
untrusted procedural language
plpythonu | 1.0 | | PL/PythonU
untrusted procedural language
(9 rows)

However when I attempt to create the following function (from the pg docs
<http://www.postgresql.org/docs/9.5/static/plpython-funcs.html>)

CREATE FUNCTION pymax (a integer, b integer)
RETURNS integer
AS $$
if a > b:
return a
return b
$$ LANGUAGE plpython3u;

the psql (or pgadmin3) terminal's connection is reset.

The python 3.3 on the path is anaconda's distb and runs fine on its own. I
couldn't find the required version of python in the postgresql docs and
used dependency walker as described here Postgres database crash when
installing plpython
<http://stackoverflow.com/questions/12010344/postgres-database-crash-when-installing-plpython?rq=1>
to
find the required dll that plpython3.dll in the server's lib/ requires.

Can anyone help me with what I have missed?

This question is also posted on stackoverflow here
<https://stackoverflow.com/questions/37382511/postgres-9-5-create-function-plpthon3u-resets-connections-to-server>
.

Thanks in advance for your help.

Many thanks