incomplete code block in layout functions tutorial

[novigit]

Hi! I was just going over the ete3 tutorial and I believe the code block under 'layout functions' is incomplete.

The import statement does not include to import TreeStyle and TextFace, despite being used later on and the abc_layout function is defined but not used anywhere. Also, n.img_style["color"] is not recognized.

I fiddled around and found these updates to get the code block working again

from ete3 import Tree, TreeStyle, TextFace

node.img_style["fgcolor"] = "red"

and

t.show(tree_style=ts, layout=abc_layout)

Please update this section of the tutorial!