How can I print to `sys.stderr` in Cython?

Question

How can I print to sys.stderr in Cython? This is my tmp_cpp.pyx file:

# tmp_cpp.pyx
# cython: language_level=2
import sys
import traceback
cimport cython

@cython.boundscheck(False)
@cython.wraparound(False)
cdef _get_num(int n):
    cdef int x = 1
    if n+x < 1:
        print('Error!!! in valid value', file=sys.stderr)
    print(n)
    return None

def get_num(n):
    _get_num(n)
    return None

And this is the compile file tmp_setup.py:

# tmp_setup.py
from distutils.core import setup, Extension
from Cython.Build import cythonize
import numpy
setup(
    name="no name",
    ext_modules = cythonize(Extension(
    'tmp_cpp',
    sources=['tmp_cpp.pyx'],
    language='c++',
    include_dirs=[numpy.get_include()],
    library_dirs=[],
    libraries=[],
    extra_compile_args=['-O3'],
    extra_link_args=[]
    )),
)

And I tried compiling it with python tmp_setup.py build_ext --inplace;

However, it returns this error:

Compiling tmp_cpp.pyx because it changed.
[1/1] Cythonizing tmp_cpp.pyx

Error compiling Cython file:
------------------------------------------------------------
...
@cython.boundscheck(False)
@cython.wraparound(False)
cdef _get_num(int n):
    cdef int x = 1
    if n+x < 1:
        print('Error!!! in valid value', file=sys.stderr)
                                            ^
------------------------------------------------------------

tmp_cpp.pyx:12:45: Expected ')', found '='
Traceback (most recent call last):
  File "/home/u_name/code/tmp_compiling/tmp_setup.py", line 7, in <module>
    ext_modules = cythonize(Extension(
  File "/usr/local/lib64/python3.9/site-packages/Cython/Build/Dependencies.py", line 1115, in cythonize
    cythonize_one(*args)
  File "/usr/local/lib64/python3.9/site-packages/Cython/Build/Dependencies.py", line 1238, in cythonize_one
    raise CompileError(None, pyx_file)
Cython.Compiler.Errors.CompileError: tmp_cpp.pyx

print('sth', file=sys.stderr) works fine in ordinary Python. Is there any simple way to fix it? I'm using Python 3.9.16 and Cython=0.29.35