def R2_SE2_FFT(f):
    """
    Compute the SE(2) Fourier Transform of f : R^2 -> R as if f is a function on SE(2).
    That is, we view f as a function on SE(2):
    f+(g) = (L_g f)(0) = f(g^{-1} 0)

    If we parameterize g = (r, theta), where r is a translation vector and theta a rotation angle,
    we see that f+ is constant along theta, because a rotation of 0 is 0.
    Therefore,
    """
    pass
