code: def dtype(self):
      if self.block is None:
          raise AssertionError("Block is None, no dtype")
  
      if not self.needs_filling:
          return self.block.dtype
      else:
          return _get_dtype(
              maybe_promote(self.block.dtype, self.block.fill_value)[0]
          )
  
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 4 for calling the JoinUnit obj's underlying member method code with example usage: obj.dtype() and returns: self, _get_dtype