code: def test_where_clause_n_prefix() -> None:
      from superset.db_engine_specs.mssql import MssqlEngineSpec
  
      dialect = mssql.dialect()
  
      # non-unicode col
      sqla_column_type = MssqlEngineSpec.get_column_types("VARCHAR(10)")
      assert sqla_column_type is not None
      type_, _ = sqla_column_type
      str_col = column("col", type_=type_)
  
      # unicode col
      sqla_column_type = MssqlEngineSpec.get_column_types("NTEXT")
      assert sqla_column_type is not None
      type_, _ = sqla_column_type
      unicode_col = column("unicode_col", type_=type_)
  
      tbl = table("tbl")
      sel = (
          select([str_col, unicode_col])
          .select_from(tbl)
          .where(str_col == "abc")
          .where(unicode_col == "abc")
      )
  
      query = str(
          sel.compile(
              dialect=dialect, compile_kwargs={"literal_binds": True}
          )
      )
      query_expected = (
          "SELECT col, unicode_col \n"
          "FROM tbl \n"
          "WHERE col = 'abc' AND unicode_col = N'abc'"
      )
      assert query == query_expected
  
imports: import unittest.mock
  from datetime import datetime
  from textwrap import dedent
  from typing import Any, Optional
  import pytest
  from sqlalchemy import column, table
  from sqlalchemy.dialects import mssql
  from sqlalchemy.dialects.mssql import DATE, NTEXT, NVARCHAR, TEXT, VARCHAR
  from sqlalchemy.sql import select
  from sqlalchemy.types import String, TypeEngine, UnicodeText
  from superset.errors import ErrorLevel, SupersetError, SupersetErrorType
  from superset.utils.core import GenericDataType
  from tests.unit_tests.db_engine_specs.utils import assert_column_spec, assert_convert_dttm
  from tests.unit_tests.fixtures.common import dttm
label_desc: Use image node_id 2 for calling a global function with example usage: test_where_clause_n_prefix() without return types