'collapsed_sidebar' cannot be modified

Hi, I don’t understand how to use the ‘collapsed_sidebar’ parameter in the various templates that are using it. I tried to create a simple panel app and to set the collapsed_sidebar parameter to True but it is returning me an error.

The code I used :

import panel as pn


template = pn.template.FastListTemplate(
template.main.append(pn.widgets.Button(name='click me'))
template.sidebar.append(pn.widgets.Button(name='click on sidebar'))
template.sidebar_width = 150
template.collapsed_sidebar = False


The error I’m having :

Traceback (most recent call last):
  File "/home/user/sandbox/./time_interval.py", line 11, in <module>
    template.collapsed_sidebar = True
  File "/home/user/.local/lib/python3.9/site-packages/param/parameterized.py", line 525, in _f
    instance_param.__set__(obj, val)
  File "/home/user/.local/lib/python3.9/site-packages/param/parameterized.py", line 527, in _f
    return f(self, obj, val)
  File "/home/user/.local/lib/python3.9/site-packages/param/parameterized.py", line 1506, in __set__
    raise TypeError("Constant parameter '%s' cannot be modified" % name)
TypeError: Constant parameter 'collapsed_sidebar' cannot be modified

Also, the various templates are describing this parameter not as an boolean but as a str, why ?