def METHOD_NAME(Phi):
    # Transform input to enforce Neumann boundary conditions.
    # copy input
    PhiOut = Phi
    # capture image size
    m = Phi.shape[0]
    n = Phi.shape[1]
    # deal with corners
    PhiOut[0, 0] = PhiOut[2, 2]
    PhiOut[0, n - 1] = PhiOut[0, -3]
    PhiOut[m - 1, 0] = PhiOut[-3, 2]
    PhiOut[m - 1, n - 1] = PhiOut[-3, -3]
    # deal with edges
    PhiOut[0, 1:-1] = PhiOut[2, 1:-1]
    PhiOut[m - 1, 1:-1] = PhiOut[m - 3, 1:-1]
    PhiOut[1:-1, 0] = PhiOut[1:-1, 2]
    PhiOut[1:-1, n - 1] = PhiOut[1:-1, n - 3]
    return PhiOut