code: public static List<AModuleModules> getModules(List<INode> ast)
  	{
  		List<AModuleModules> modules = new LinkedList<>();
  
  		for (INode n : ast)
  		{
  			if (n instanceof AModuleModules)
  			{
  				modules.add((AModuleModules) n);
  			}
  		}
  
  		return modules;
  	}
docs: Convenience method for extracting the VDM module definitions from a list of VDM nodes.
  
  @param ast
  A list of VDM nodes.
  @return The module definitions extracted from <code>ast</code>.