Don`t understand the group_col about scikit-posthocs HOT 2 CLOSED

import scikit_posthocs as sp
import pandas as pd
x = pd.DataFrame({"k": [1, 2, 4, 5, 6], "j": [1, 3, 5, 7, 66], "m": [11, 222, 444, 5655, 777]})
x = x.melt(var_name='groups', value_name='values')
sp.posthoc_conover(x, val_col='values', group_col='groups')

import scikit_posthocs as sp
x = [[1, 2, 4, 5, 6], [1, 3, 5, 7, 66], [11, 222, 444, 5655, 777]]
sp.posthoc_conover(x)

import scikit_posthocs as sp
x = [[1, 2, 4, 5, 6], [1, 3, 5, 7, 66], [11, 222, 444, 5655, 777]]
results = sp.posthoc_conover(x)
pd.DataFrame(results, index=['k', 'j', 'm'], columns=['k', 'j', 'm'])

import scikit_posthocs as sp
import numpy as np
x = [[1, 2, 4, 5, 6], [1, 3, 5, 7, 66], [11, 222, 444, 5655, 777]]
groups  = [['k'] * 5, ['j'] * 5, ['m'] * 5]
data = pd.DataFrame([np.ravel(x), np.ravel(groups)], index=['values', 'groups']).T
sp.posthoc_conover(data, val_col='values', group_col='groups')