code: def get_default_ENV(env):
      
      global default_ENV
      try:
          return env['ENV']
      except KeyError:
          if not default_ENV:
              import SCons.Environment
              # This is a hideously expensive way to get a default shell
              # environment.  What it really should do is run the platform
              # setup to get the default ENV.  Fortunately, it's incredibly
              # rare for an Environment not to have a shell environment, so
              # we're not going to worry about it overmuch.
              default_ENV = SCons.Environment.Environment()['ENV']
          return default_ENV
docs: A fiddlin' little function that has an 'import SCons.Environment' which
      can't be moved to the top level without creating an import loop.  Since
      this import creates a local variable named 'SCons', it blocks access to
      the global variable, so we move it here to prevent complaints about local
      variables being used uninitialized.