def METHOD_NAME(self, a, axes=None, workers=-1):
    axes = axes or tuple(range(a.ndim))
    # FFTW_BACKWARD requires complex input array, cast as needed.
    # See https://pyfftw.readthedocs.io/en/latest/source/pyfftw/pyfftw.html#scheme-table
    comp_type = complex_type(a.dtype)
    a = a.astype(comp_type, copy=False)
    mutex.acquire()
    try:
        a_ = pyfftw.empty_aligned(a.shape, dtype=comp_type)
        b = pyfftw.empty_aligned(a.shape, dtype=comp_type)
        cls = pyfftw.FFTW(
            a_, b, axes=axes, direction="FFTW_BACKWARD", threads=_workers(workers)
        )
        cls(a, b)
    finally:
        mutex.release()
    return b