update improvement

update.py

from cloudify import ctx

@operation
def some_op(**kwargs):
    # do wonderful things

    def handler(current_runtime_properties):
        # make modification
        current_runtime_properties.setdefault('prop', []).append('some_value')

    # The implementation will take care of retrying the handler specifically when a ConflictError occurs    
    ctx.instance.update(update_handler=handler)