def second_order_moments_u(adata):
if '<STR_LIT>' not in adata.uns:<EOL><INDENT>raise ValueError('<STR_LIT>')<EOL><DEDENT>connectivities = get_connectivities(adata)<EOL>u = csr_matrix(adata.layers['<STR_LIT>'])<EOL>Muu = csr_matrix.dot(connectivities, u.multiply(u)).astype(np.float32).A<EOL>return Muu<EOL>
Computes second order moments for stochastic velocity estimation.

    Arguments
    ---------
    adata: `AnnData`
        Annotated data matrix.

    Returns
    -------
    Muu: Second order moments for unspliced abundances