curr_chart = m.find('-isa', 'Stateflow.Chart', '-and', 'Name', 'chart_if_test_0');
curr_chart.view;
You first need to find the chart, then inspect it with view. I think if you use add_block you are using a Simulink command that probably returns the handler instead of the real object. Afterwards you can use constructors on object curr_chart.
