Function `sampleby` return parity

df = self.spark.createDataFrame([Row(a=i, b=(i % 3)) for i in range(100)])
sampled = df.stat.sampleBy("b", fractions={0: 0.5, 1: 0.5}, seed=0)
self.assertTrue(sampled.count() == 35)

Traceback (most recent call last):
  File "/Users/s.singh/personal/spark-oss/python/pyspark/sql/tests/test_functions.py", line 202, in test_sampleby
    self.assertTrue(sampled.count() == 35)
AssertionError: False is not true