code: @Override
  	public String getObligation(String root)
  	{
  		StringBuilder result = new StringBuilder();
  		String spacing = "  ";
  		String indent = "";
  		StringBuilder tail = new StringBuilder();
  
  		for (IPOContext ctxt : this)
  		{
  			String po = ctxt.getContext();
  
  			if (po.length() > 0)
  			{
  				result.append(indent);
  				result.append("(");
  				result.append(indentNewLines(po, indent));
  				result.append("\n");
  				indent = indent + spacing;
  				tail.append(")");
  			}
  		}
  
  		result.append(indent);
  		result.append(indentNewLines(root, indent));
  		result.append(tail);
  		result.append("\n");
  
  		return result.toString();
  	}
docs: /*
  (non-Javadoc)
  @see org.overture.pog.IPOContextStack#getObligation(java.lang.String)