def genSankey(df,cat_cols=[],value_cols='',title='Sankey Diagram'):
    # maximum of 6 value cols -> 6 colors
    colorPalette = ['#ff0000','#00ff00','#0000ff','#ffff00','#00ffff']
    labelList = []
    colorNumList = []
    for catCol in cat_cols:
        labelListTemp =  list(set(df[catCol].values))
        colorNumList.append(len(labelListTemp))
        labelList = labelList + labelListTemp

    # remove duplicates from labelList
    labelList = list(dict.fromkeys(labelList))

    # define colors based on number of levels
    colorList = []
    for idx, colorNum in enumerate(colorNumList):
        colorList = colorList + [colorPalette[idx]]*colorNum

    # transform df into a source-target pair
    for i in range(len(cat_cols)-1):
        if i==0:
            sourceTargetDf = df[[cat_cols[i],cat_cols[i+1],value_cols]]
            sourceTargetDf.columns = ['source','target','count']
        else:
            tempDf = df[[cat_cols[i],cat_cols[i+1],value_cols]]
            tempDf.columns = ['source','target','count']
            sourceTargetDf = pd.concat([sourceTargetDf,tempDf])
        sourceTargetDf = sourceTargetDf.groupby(['source','target']).agg({'count':'sum'}).reset_index()

    # add index for source-target pair
    sourceTargetDf['sourceID'] = sourceTargetDf['source'].apply(lambda x: labelList.index(x))
    sourceTargetDf['targetID'] = sourceTargetDf['target'].apply(lambda x: labelList.index(x))

    #Source Color
    source_color = sourceTargetDf.source.unique()
    diccionario = {}
    for j in range(len(source_color)):
        diccionario.update({source_color[j]:'rgb({}, {}, {}, 0.05)'.format(np.random.randint(low = 0, high = 255),
                                                          np.random.randint(low = 0, high = 255),
                                                          np.random.randint(low = 0, high = 255))})

    sourceTargetDf['colors'] = sourceTargetDf['source'].map(diccionario)

    # creating the sankey diagram
    data = dict(
        type='sankey',
        node = dict(
          pad = 15,
          thickness = 20,
          line = dict(
            color = "black",
            width = 0.5
          ),
          label = labelList,
          color = colorList
        ),
        link = dict(
          source = sourceTargetDf['sourceID'],
          target = sourceTargetDf['targetID'],
          value = sourceTargetDf['count'],
          color = sourceTargetDf['colors'].dropna(axis=0, how='any')
        )
      )

    layout =  dict(
        title = title,
        font = dict(
          size = 10
        )
    )

    fig = dict(data=[data], layout=layout)


    return fig