def add_marker(x, y, z):
    """ Create a plotly marker dict. """

    return {
        "x": [x],
        "y": [y],
        "z": [z],
        "mode": "markers",
        "marker": {"size": 25, "line": {"width": 3}},
        "name": "Marker",
        "type": "scatter3d",
        "text": ["Click point to remove annotation"],
    }