"By" Column Is Not Properly Removed

[r0f1]

I created a column key to print different groups of my dataset. However, the key is still present in the histograms (orange bars).

import joypy
from sklearn.datasets import load_iris

df = load_iris(as_frame=True).data
df["key"] = df.index % 3
df = df[["sepal length (cm)", "key"]]
_ = joypy.joyplot(df, by="key", hist=True)

[leotac]

Indeed it looks like a bug. Let me fix it.