code: def _default_sysroot(cc):
      """Returns the root of the default SDK for this system, or '/'"""
      global _cache_default_sysroot
  
      if _cache_default_sysroot is not None:
          return _cache_default_sysroot
  
      contents = _read_output("%s -c -E -v - </dev/null" % (cc,), True)
      in_incdirs = False
      for line in contents.splitlines():
          if line.startswith("#include <...>"):
              in_incdirs = True
          elif line.startswith("End of search list"):
              in_incdirs = False
          elif in_incdirs:
              line = line.strip()
              if line == "/usr/include":
                  _cache_default_sysroot = "/"
              elif line.endswith(".sdk/usr/include"):
                  _cache_default_sysroot = line[:-12]
      if _cache_default_sysroot is None:
          _cache_default_sysroot = "/"
  
      return _cache_default_sysroot
  
imports: import os
  import re
  import sys
label_desc: Use image node_id 8 for calling a global function with example usage: _default_sysroot(cc) and returns: _cache_default_sysroot, _cache_default_sysroot