'Provides default cache_timeout for the :func:`send_file` functions.
By default, this function returns ``SEND_FILE_MAX_AGE_DEFAULT`` from
the configuration of :data:`~flask.current_app`.
Static file functions such as :func:`send_from_directory` use this
function, and :func:`send_file` calls this function on
:data:`~flask.current_app` when the given cache_timeout is ``None``. If a
cache_timeout is given in :func:`send_file`, that timeout is used;
otherwise, this method is called.
This allows subclasses to change the behavior when sending files based
on the filename.  For example, to set the cache timeout for .js files
to 60 seconds::
class MyFlask(flask.Flask):
def get_send_file_max_age(self, name):
if name.lower().endswith(\'.js\'):
return 60
return flask.Flask.get_send_file_max_age(self, name)
.. versionadded:: 0.9'

def get_send_file_max_age(self, filename):

    return total_seconds(current_app.send_file_max_age_default)
