v1.6.12 (v1.5.21 for Python 3.7)

v1.6.12

• Allow nested chunk generators.
  This patch more gracefully handles labels for situations with nested chunk generators and adds and explicit test for this scenario.

  import meerschaum as mrsm
  pipe = mrsm.Pipe('foo', 'bar', instance='sql:memory')
  
  docs = [{'color': 'red'}, {'color': 'green'}]
  num_chunks = 3
  num_batches = 2
  
  def build_chunks():
      return (
          [
              {'chunk_ix': chunk_ix, **doc}
              for doc in docs
          ]
          for chunk_ix in range(num_chunks)
      )
  
  batches = (
      (
          [
              {'batch_ix': batch_ix, **doc}
              for doc in chunk
          ]
          for chunk in build_chunks()
      )
      for batch_ix in range(num_batches)
  )
  
  pipe.sync(batches)
  print(pipe.get_data())
  #     batch_ix  chunk_ix  color
  # 0          0         0    red
  # 1          0         0  green
  # 2          0         1    red
  # 3          0         1  green
  # 4          0         2    red
  # 5          0         2  green
  # 6          1         0    red
  # 7          1         0  green
  # 8          1         1    red
  # 9          1         1  green
  # 10         1         2    red
  # 11         1         2  green