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 _validate(self, validate):
      # Check uniqueness of each
      if self.left_index:
          left_unique = self.orig_left.index.is_unique
      else:
          left_unique = MultiIndex.from_arrays(
              self.left_join_keys
          ).is_unique
  
      if self.right_index:
          right_unique = self.orig_right.index.is_unique
      else:
          right_unique = MultiIndex.from_arrays(
              self.right_join_keys
          ).is_unique
  
      # Check data integrity
      if validate in ["one_to_one", "1:1"]:
          if not left_unique and not right_unique:
              raise MergeError(
                  "Merge keys are not unique in either left"
                  " or right dataset; not a one-to-one merge"
              )
          elif not left_unique:
              raise MergeError(
                  "Merge keys are not unique in left dataset;"
                  " not a one-to-one merge"
              )
          elif not right_unique:
              raise MergeError(
                  "Merge keys are not unique in right dataset;"
                  " not a one-to-one merge"
              )
  
      elif validate in ["one_to_many", "1:m"]:
          if not left_unique:
              raise MergeError(
                  "Merge keys are not unique in left dataset;"
                  " not a one-to-many merge"
              )
  
      elif validate in ["many_to_one", "m:1"]:
          if not right_unique:
              raise MergeError(
                  "Merge keys are not unique in right dataset;"
                  " not a many-to-one merge"
              )
  
      elif validate in ["many_to_many", "m:m"]:
          pass
  
      else:
          raise ValueError("Not a valid argument for validate")
  
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 12 for calling the _MergeOperation obj's underlying member method code with example usage: obj._validate(validate) without return types