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matplotlib.axes.Axes.add_artist
Axes.add_artist(a)- 
    
Add any
Artistto the axes.Use
add_artistonly for artists for which there is no dedicated “add” method; and if necessary, use a method such asupdate_datalimorupdate_datalim_numerixto manually update the dataLim if the artist is to be included in autoscaling.Returns the artist.
 
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 http://matplotlib.org/2.0.2/api/_as_gen/matplotlib.axes.Axes.add_artist.html