human
I wrote the below code

    qmat = (AtA / s)
    m = BI.shape[0]
    qmat[0:m, 0:m] += BI
    ix = np.arange(m, A.shape[1])
    qmat[(ix, ix)] += di
    if sparse.issparse(A):
        qi = sparse.linalg.inv(qmat)
        qmati = A.dot(qi.T).T
    else:
        qmati = np.linalg.solve(qmat, A.T)
    def solver(rhs):
        if sparse.issparse(A):
            ql = qmati.dot(rhs)
            ql = A.dot(ql)
        else:
            ql = np.dot(qmati, rhs)
            ql = np.dot(A, ql)
        rslt = ((rhs / s) - (ql / (s ** 2)))
        if sparse.issparse(rslt):
            rslt = np.asarray(rslt.todense())
        return rslt
    return solver

What's a good function header?

=====
Here's a good function header?
assistant
#Here's a good function header.

def _smw_solver(s, A, AtA, BI, di):