How to use the scons.scons-local-250.SCons.Environment.BuilderDict function in SCons

def Clone(self, tools=[], toolpath=None, parse_flags = None, **kw):
        """Return a copy of a construction Environment.  The
        copy is like a Python "deep copy"--that is, independent
        copies are made recursively of each objects--except that
        a reference is copied when an object is not deep-copyable
        (like a function).  There are no references to any mutable
        objects in the original Environment.
        """

        builders = self._dict.get('BUILDERS', {})

        clone = copy.copy(self)
        # BUILDERS is not safe to do a simple copy
        clone._dict = semi_deepcopy_dict(self._dict, ['BUILDERS'])
        clone._dict['BUILDERS'] = BuilderDict(builders, clone)

        # Check the methods added via AddMethod() and re-bind them to
        # the cloned environment.  Only do this if the attribute hasn't
        # been overwritten by the user explicitly and still points to
        # the added method.
        clone.added_methods = []
        for mw in self.added_methods:
            if mw == getattr(self, mw.name):
                clone.added_methods.append(mw.clone(clone))

        clone._memo = {}

        # Apply passed-in variables before the tools
        # so the tools can use the new variables
        kw = copy_non_reserved_keywords(kw)
        new = {}

def Replace(self, **kw):
        """Replace existing construction variables in an Environment
        with new construction variables and/or values.
        """
        try:
            kwbd = kw['BUILDERS']
        except KeyError:
            pass
        else:
            kwbd = BuilderDict(kwbd,self)
            del kw['BUILDERS']
            self.__setitem__('BUILDERS', kwbd)
        kw = copy_non_reserved_keywords(kw)
        self._update(semi_deepcopy(kw))
        self.scanner_map_delete(kw)

def Replace(self, **kw):
        """Replace existing construction variables in an Environment
        with new construction variables and/or values.
        """
        try:
            kwbd = kw['BUILDERS']
        except KeyError:
            pass
        else:
            kwbd = BuilderDict(kwbd,self)
            del kw['BUILDERS']
            self.__setitem__('BUILDERS', kwbd)
        kw = copy_non_reserved_keywords(kw)
        self._update(semi_deepcopy(kw))
        self.scanner_map_delete(kw)

def _set_BUILDERS(env, key, value):
    try:
        bd = env._dict[key]
        for k in bd.keys():
            del bd[k]
    except KeyError:
        bd = BuilderDict(kwbd, env)
        env._dict[key] = bd
    for k, v in value.items():
        if not SCons.Builder.is_a_Builder(v):
            raise SCons.Errors.UserError('%s is not a Builder.' % repr(v))
    bd.update(value)

def _set_BUILDERS(env, key, value):
    try:
        bd = env._dict[key]
        for k in bd.keys():
            del bd[k]
    except KeyError:
        bd = BuilderDict(kwbd, env)
        env._dict[key] = bd
    for k, v in value.items():
        if not SCons.Builder.is_a_Builder(v):
            raise SCons.Errors.UserError('%s is not a Builder.' % repr(v))
    bd.update(value)

self._dict = semi_deepcopy(SCons.Defaults.ConstructionEnvironment)
        self._init_special()
        self.added_methods = []

        # We don't use AddMethod, or define these as methods in this
        # class, because we *don't* want these functions to be bound
        # methods.  They need to operate independently so that the
        # settings will work properly regardless of whether a given
        # target ends up being built with a Base environment or an
        # OverrideEnvironment or what have you.
        self.decide_target = default_decide_target
        self.decide_source = default_decide_source

        self.copy_from_cache = default_copy_from_cache

        self._dict['BUILDERS'] = BuilderDict(self._dict['BUILDERS'], self)

        if platform is None:
            platform = self._dict.get('PLATFORM', None)
            if platform is None:
                platform = SCons.Platform.Platform()
        if SCons.Util.is_String(platform):
            platform = SCons.Platform.Platform(platform)
        self._dict['PLATFORM'] = str(platform)
        platform(self)

        self._dict['HOST_OS']      = self._dict.get('HOST_OS',None)
        self._dict['HOST_ARCH']    = self._dict.get('HOST_ARCH',None)

        # Now set defaults for TARGET_{OS|ARCH}
        self._dict['TARGET_OS']      = self._dict.get('TARGET_OS',None)
        self._dict['TARGET_ARCH']    = self._dict.get('TARGET_ARCH',None)