def member(L, A):
    """
    Return the index of the first appearance of array A in L.

    Parameters
    ----------
    L : list of np.array
        list on which to perform the search
    A : np.array
        the target array

    Returns
    -------
    position : int or None
        the index of the first appearance of array A in list L, or
        None if A is not in L.

    """
    for i, B in enumerate(L):
        if (A == B).all():
            return i
    return None