def get_default_ENV(env):
    """
    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.
    """
    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
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.