code: def __init__(self, block, shape, indexers=None):
      # Passing shape explicitly is required for cases when block is None.
      if indexers is None:
          indexers = {}
      self.block = block
      self.indexers = indexers
      self.shape = shape
  
imports: from collections import defaultdict
  import copy
  import numpy
  from pandas._libs import internals, tslibs
  from pandas.util._decorators import cache_readonly
  from pandas.core.dtypes.cast import maybe_promote
  from pandas.core.dtypes.common import _get_dtype, is_categorical_dtype, is_datetime64_dtype, is_datetime64tz_dtype, is_extension_array_dtype, is_float_dtype, is_numeric_dtype, is_sparse, is_timedelta64_dtype
  import pandas.core.dtypes.concat
  from pandas.core.dtypes.missing import isna
  import pandas.core.algorithms
label_desc: Use image node_id 1 to create a new JoinUnit object from inherited base classes: object with example: obj = JoinUnit(block, shape, indexers)