class_docstr: Perform a database (SQL) merge operation between two DataFrame objects
  using either columns as keys or their row indexes
class_docstr_tok: ["Perform","a","database","(","SQL",")","merge","operation","between","two","DataFrame","objects","using","either","columns","as","keys","or","their","row","indexes"]
code: def _indicator_post_merge(self, result):
      result["_left_indicator"] = result["_left_indicator"].fillna(0)
      result["_right_indicator"] = result["_right_indicator"].fillna(0)
  
      result[self.indicator_name] = Categorical(
          (result["_left_indicator"] + result["_right_indicator"]),
          categories=[1, 2, 3],
      )
      result[self.indicator_name] = result[
          self.indicator_name
      ].cat.rename_categories(["left_only", "right_only", "both"])
  
      result = result.drop(
          labels=["_left_indicator", "_right_indicator"], axis=1
      )
      return result
  
imports: import copy
  import string
  import warnings
  import numpy
  from pandas._libs import hashtable, join, lib
  import pandas.compat
  from pandas.compat import filter, lzip, map, range, zip
  from pandas.errors import MergeError
  from pandas.util._decorators import Appender, Substitution
  from pandas.core.dtypes.common import ensure_float64, ensure_int64, ensure_object, is_array_like, is_bool, is_bool_dtype, is_categorical_dtype, is_datetime64_dtype, is_datetime64tz_dtype, is_datetimelike, is_dtype_equal, is_extension_array_dtype, is_float_dtype, is_int64_dtype, is_integer, is_integer_dtype, is_list_like, is_number, is_numeric_dtype, is_object_dtype, needs_i8_conversion
  from pandas.core.dtypes.missing import isnull, na_value_for_dtype
  from pandas import Categorical, DataFrame, Index, MultiIndex, Series, Timedelta
  import pandas.core.algorithms
  from pandas.core.arrays.categorical import _recode_for_categories
  import pandas.core.common
  from pandas.core.frame import _merge_doc
  from pandas.core.internals import concatenate_block_managers, items_overlap_with_suffix
  import pandas.core.sorting
  from pandas.core.sorting import is_int64_overflow_possible
label_desc: Use image node_id 4 for calling the _MergeOperation obj's underlying member method code with example usage: obj._indicator_post_merge(result) and returns: result