def get_nonzero_either_mask(vector_a, vector_b):
    """Returns a numpy array of boolean values indicating where values in two
    vectors are both greater than zero.

    Parameters
    ----------
    vector_a : numpy.ndarray
        Array of counts or RPKM

    vector_b : numpy.ndarray
        Array of counts or RPKM

    Returns
    -------
    numpy.ndarray
        Boolean array that is `True` where both `vector_a` and `vector_b`
        have values greater than zero, and `False` elsewhere.
    """
    return (vector_a > 0) & (vector_b > 0)