It seems that initializing brython requires to be done like so:
<body onload="brython()">
I tried calling brython() in js in another <script> after having linked brython.js but it doesn't seem to get called.
When I finally call brython myself in the browser console, it calls brython, and even executes my python code.
To give a full example of what doesn't work, here is an example. I may be lacking some basic knowledge of how and when javascript is compiled and executed...
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript" src="/js/brython.js"></script>
</head>
<!-- <body onload="brython()"> -->
<body>
<script type="text/javascript">
console.log("calling brython() here");
brython();
console.log("I just called brython()");
</script>
<script type="text/python">
from browser import document, alert
def echo(*args):
alert("Hello {} !".format(document["zone"].value))
document["test"].bind("click", echo)
print("what")
</script>
<p>Your name is : <input id="zone" autocomplete="off">
<button id="test">clic !</button>
</body>
</html>