code: def get_dataset():
      global _dataset
      if _dataset is None:
          _dataset = hl.read_matrix_table(
              resource("split-multi-sample.vcf.mt")
          ).select_globals()
      return _dataset
  
imports: from typing import Callable, TypeVar
  from typing_extensions import ParamSpec
  import os
  from timeit import default_timer
  import unittest
  import pytest
  from hailtop.hail_decorator import decorator
  from hail.utils.java import choose_backend
  import hail
label_desc: Use image node_id 7 for calling a global function with example usage: get_dataset() and returns: _dataset