columnConfigs = new HashMap<>();
for (Map<String,Object> spec : yaml.columnspec)
{
lowerCase(spec);
String name = (String) spec.remove("name");
DistributionFactory population = !spec.containsKey("population") ? null : OptionDistribution.get((String) spec.remove("population"));
DistributionFactory size = !spec.containsKey("size") ? null : OptionDistribution.get((String) spec.remove("size"));
DistributionFactory clustering = !spec.containsKey("cluster") ? null : OptionDistribution.get((String) spec.remove("cluster"));
if (!spec.isEmpty())
throw new IllegalArgumentException("Unrecognised option(s) in column spec: " + spec);
if (name == null)
throw new IllegalArgumentException("Missing name argument in column spec");