Please note that after the first part trigger has been added, subsequent part triggers must include a boolean to indicate whether the part expression is to be 'anded' or 'ored'
task2 = ecflow.Task("t2")
task2.add_part_trigger( "t1 == complete")
task2.add_part_trigger( "t2 == active", True) # here True means add as 'AND'
task2.add_part_trigger( "t3 == active", False) # here False means add as 'OR'
complete expression is: (t1 == complete and t2 == active or t3 == active)