to_undirected(COLLAPSE)
=======================

Creator "igraph version @VERSION@ unittest"
Version 1
graph
[
  directed 0
  node
  [
    id 0
  ]
  node
  [
    id 1
  ]
  node
  [
    id 2
  ]
  node
  [
    id 3
  ]
  edge
  [
    source 1
    target 0
    weight 6
  ]
  edge
  [
    source 1
    target 1
    weight 6
  ]
]

to_undirected(MUTUAL)
=====================

Creator "igraph version @VERSION@ unittest"
Version 1
graph
[
  directed 0
  node
  [
    id 0
  ]
  node
  [
    id 1
  ]
  node
  [
    id 2
  ]
  node
  [
    id 3
  ]
  edge
  [
    source 1
    target 0
    weight 5
  ]
  edge
  [
    source 1
    target 1
    weight 2
  ]
  edge
  [
    source 1
    target 1
    weight 4
  ]
]

to_undirected(EACH)
===================

Creator "igraph version @VERSION@ unittest"
Version 1
graph
[
  directed 0
  node
  [
    id 0
  ]
  node
  [
    id 1
  ]
  node
  [
    id 2
  ]
  node
  [
    id 3
  ]
  edge
  [
    source 1
    target 0
    weight 1
  ]
  edge
  [
    source 1
    target 0
    weight 2
  ]
  edge
  [
    source 1
    target 0
    weight 3
  ]
  edge
  [
    source 1
    target 1
    weight 4
  ]
  edge
  [
    source 1
    target 1
    weight 2
  ]
]