code: def test_first_token_predicate(self):
      assert fn.firstTokenPredicate("donald") == {"donald"}
      assert fn.firstTokenPredicate("don ald") == {"don"}
      assert fn.firstTokenPredicate("do\nal d") == {"do"}
      assert fn.firstTokenPredicate("go-of y  ") == {"go"}
      assert fn.firstTokenPredicate(" cip   ciop ") == frozenset()
  
imports: import unittest
  from dedupe import predicate_functions
  from dedupe.cpredicates import ngrams
label_desc: Use image node_id 3 for calling the TestPredicateFunctions obj's underlying member method code with example usage: obj.test_first_token_predicate() without return types