[Python] Critical points of an absolute value periodic function in Sympy

I want to look for the critical points of the following periodic function abs(sin(x)) for x in the Real set.

So far I have tried:

from sympy import *

x = Symbol("x")

f = abs(sin(x))

solveset(diff(f), x, S.Reals)


with no luck, I then tried to unpack the absolute value into a piecewise function:

as_piece = Piecewise((sin(x), sin(x)>=0), (-sin(x), sin(x)<0))

solveset(diff(as_piece), x, S.Reals)


and again solveset cannot solve it. The interesting thing is that solve is able to solve as_piece but of course returns only the first two critical points as its output is not a set.

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