terminate called after throwing an instance of 'std::length_error'
  what():  basic_string::_S_create
<?xml version="1.0" encoding="UTF-8"?>
<graphml xmlns="http://graphml.graphdrawing.org/xmlns" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://graphml.graphdrawing.org/xmlns http://graphml.graphdrawing.org/xmlns/1.0/graphml.xsd">
  <key id="key0" for="node" attr.name="foo" attr.type="string" />
  <graph id="G" edgedefault="directed" parse.nodeids="free" parse.edgeids="canonical" parse.order="nodesfirst">
    <node id="n0">