code: def get_openmp_flag():
      if sys.platform == "win32":
          return ["/openmp"]
      elif sys.platform == "darwin" and "openmp" in os.getenv(
          "CPPFLAGS", ""
      ):
          # -fopenmp can't be passed as compile flag when using Apple-clang.
          # OpenMP support has to be enabled during preprocessing.
          #
          # For example, our macOS wheel build jobs use the following environment
          # variables to build with Apple-clang and the brew installed "libomp":
          #
          # export CPPFLAGS="$CPPFLAGS -Xpreprocessor -fopenmp"
          # export CFLAGS="$CFLAGS -I/usr/local/opt/libomp/include"
          # export CXXFLAGS="$CXXFLAGS -I/usr/local/opt/libomp/include"
          # export LDFLAGS="$LDFLAGS -Wl,-rpath,/usr/local/opt/libomp/lib
          #                          -L/usr/local/opt/libomp/lib -lomp"
          return []
      # Default flag for GCC and clang:
      return ["-fopenmp"]
  
imports: import os
  import sys
  import textwrap
  import warnings
  from .pre_build_helpers import compile_test_program
label_desc: Use image node_id 1 for calling a global function with example usage: get_openmp_flag() and returns: list, list, list