['he', 'keep', 'stumble', 'word', 'EmptyParameter']
['<PRP>', 'keep-15.2', 'run-51.3.2', "Synset('unit_of_measurement.n.01')", 'EmptyParameter']
He keeps stumbling over his words and is nervous.
<PRP> keeps stumbling over <PRP> Synset('unit_of_measurement.n.01') and is Synset('nervous.a.03').