Parameters
    ----------
    mst_wood : list of dictionarys
    i : int
        Number of the stroke where one mst gets split

    Returns
    -------
    tuple :
        (mst index, node index)

def find_split_node(mst_wood, i):
    """
    Parameters
    ----------
    mst_wood : list of dictionarys
    i : int
        Number of the stroke where one mst gets split

    Returns
    -------
    tuple :
        (mst index, node index)
    """
    for mst_index, mst in enumerate(mst_wood):
        if i in mst['strokes']:
            return (mst_index, mst['strokes'].index(i))
    raise ValueError('%i was not found as stroke index.' % i)