code: def table_scan_prev_non_null():
      ht = hl.utils.range_table(100000000, n_partitions=10)
      ht = ht.annotate(x=hl.range(0, ht.idx % 25))
      ht = ht.annotate(y=hl.scan._prev_nonnull(ht.row))
      ht._force_count()
  
imports: from os import path
  from tempfile import TemporaryDirectory
  import hail
  from .resources import *
  from .utils import benchmark
label_desc: Use image node_id 57 for calling a global function with example usage: table_scan_prev_non_null() without return types