code: def _build_extract_expression(
      date_string: str, date_part: DatePart
  ) -> SqlExtractExpression:
      cast_expr = SqlCastToTimestampExpression(
          SqlStringLiteralExpression(literal_value=date_string)
      )
      return SqlExtractExpression(date_part=date_part, arg=cast_expr)
  
file_path: metricflow/metricflow/test/sql_clients/test_date_time_operations.py
imports: from __future__ import annotations
  import logging
  from typing import Any
  import pandas
  import pytest
  from dbt_semantic_interfaces.type_enums.date_part import DatePart
  from metricflow.protocols.sql_client import SqlClient
  from metricflow.sql.sql_exprs import SqlCastToTimestampExpression, SqlDateTruncExpression, SqlExtractExpression, SqlStringLiteralExpression
  from metricflow.time.time_granularity import TimeGranularity
label_desc: Use image node_id 6 for calling a global function with example usage: _build_extract_expression(date_string, date_part) and returns: SqlExtractExpression