def matrix_wrapper(input_tuple):
    """ Parallel wrapper for matrix formation.

    This wrapper is used whenever a pmap/map-type function is used to make
    matrices for each cell in parallel.

    Parameters
    ----------
    input_tuple : Tuple
        Index 0 is the chain (depletion_chain.DepletionChain), index 1 is the
        reaction rate array (reaction_rates.ReactionRates), index 2 is the
        cell_id.

    Returns
    -------
    scipy.sparse.csr_matrix
        The matrix for this reaction rate.
    """
    return input_tuple[0].form_matrix(input_tuple[1], input_tuple[2])