<｜begin▁of▁sentence｜>### Instruction:
Given a tree graph with 5 vertices, where each non-leaf vertex has 2 children, demonstrate how to draw undirected edges with varying alpha transparency using igraph's AlphaVaryingEdgeDrawer.
### Response:
from igraph import Graph, Plot
from igraph.drawing.edge import AlphaVaryingEdgeDrawer
from igraph.drawing.vertex import ShapeDrawer

# Create an igraph graph
g = Graph.Tree(5, 2) # Creating a tree with 5 vertices and children having 2 branches each

# Initialize a plot with a specific size
plot = Plot(bbox=(300, 300), background='white')

# Assign a layout for our graph
layout = g.layout('kk')

# Create a shape drawer for our vertices
vertex_drawer = ShapeDrawer()

# Fetch Cairo context from the plot
ctx = plot.context

# Create an edge drawer with varying alpha
alpha_edge_drawer = AlphaVaryingEdgeDrawer(ctx)

# Draw the graph edges
for edge in g.get_edgelist():
    start, end = layout[edge[0]], layout[edge[1]]
    alpha_edge_drawer.draw_undirected_edge(start, end, 0.5) # 0.5 is the alpha transparency

# Draw the graph vertices
for idx, (x, y) in enumerate(layout):
    vertex_drawer.draw_vertex(ctx, (x, y))
    vertex_drawer.draw_text(ctx, (x, y), str(idx))

# Save the plot to a file
plot.save('tree_with_alpha_edges.png')
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