How to use the jinja2._compat.iteritems function in Jinja2

def pop_scope(self, aliases, frame):
        """Restore all aliases and delete unused variables."""
        for name, alias in iteritems(aliases):
            self.writeline('l_%s = %s' % (name, alias))
        to_delete = set()
        for name in frame.identifiers.declared_locally:
            if name not in aliases:
                to_delete.add('l_' + name)
        if to_delete:
            # we cannot use the del statement here because enclosed
            # scopes can trigger a SyntaxError:
            #   a = 42; b = lambda: a; del a
            self.writeline(' = '.join(to_delete) + ' = missing')

self.write(', %s=%s' % (key, value))
        if node.dyn_args:
            self.write(', *')
            self.visit(node.dyn_args, frame)

        if kwarg_workaround:
            if node.dyn_kwargs is not None:
                self.write(', **dict({')
            else:
                self.write(', **{')
            for kwarg in node.kwargs:
                self.write('%r: ' % kwarg.key)
                self.visit(kwarg.value, frame)
                self.write(', ')
            if extra_kwargs is not None:
                for key, value in iteritems(extra_kwargs):
                    self.write('%r: %s, ' % (key, value))
            if node.dyn_kwargs is not None:
                self.write('}, **')
                self.visit(node.dyn_kwargs, frame)
                self.write(')')
            else:
                self.write('}')

        elif node.dyn_kwargs is not None:
            self.write(', **')
            self.visit(node.dyn_kwargs, frame)

'}':            TOKEN_RBRACE,
    '==':           TOKEN_EQ,
    '!=':           TOKEN_NE,
    '>':            TOKEN_GT,
    '>=':           TOKEN_GTEQ,
    '<':            TOKEN_LT,
    '<=':           TOKEN_LTEQ,
    '=':            TOKEN_ASSIGN,
    '.':            TOKEN_DOT,
    ':':            TOKEN_COLON,
    '|':            TOKEN_PIPE,
    ',':            TOKEN_COMMA,
    ';':            TOKEN_SEMICOLON
}

reverse_operators = dict([(v, k) for k, v in iteritems(operators)])
assert len(operators) == len(reverse_operators), 'operators dropped'
operator_re = re.compile('(%s)' % '|'.join(re.escape(x) for x in
                         sorted(operators, key=lambda x: -len(x))))

ignored_tokens = frozenset([TOKEN_COMMENT_BEGIN, TOKEN_COMMENT,
                            TOKEN_COMMENT_END, TOKEN_WHITESPACE,
                            TOKEN_WHITESPACE, TOKEN_LINECOMMENT_BEGIN,
                            TOKEN_LINECOMMENT_END, TOKEN_LINECOMMENT])
ignore_if_empty = frozenset([TOKEN_WHITESPACE, TOKEN_DATA,
                             TOKEN_COMMENT, TOKEN_LINECOMMENT])


def _describe_token_type(token_type):
    if token_type in reverse_operators:
        return reverse_operators[token_type]
    return {

is linked to plus optional extra extensions.

        Creating overlays should happen after the initial environment was set
        up completely.  Not all attributes are truly linked, some are just
        copied over so modifications on the original environment may not shine
        through.
        """
        args = dict(locals())
        del args['self'], args['cache_size'], args['extensions']

        rv = object.__new__(self.__class__)
        rv.__dict__.update(self.__dict__)
        rv.overlayed = True
        rv.linked_to = self

        for key, value in iteritems(args):
            if value is not missing:
                setattr(rv, key, value)

        if cache_size is not missing:
            rv.cache = create_cache(cache_size)
        else:
            rv.cache = copy_cache(self.cache)

        rv.extensions = {}
        for key, value in iteritems(self.extensions):
            rv.extensions[key] = value.bind(rv)
        if extensions is not missing:
            rv.extensions.update(load_extensions(rv, extensions))

        return _environment_sanity_check(rv)

def has_safe_repr(value):
    """Does the node have a safe representation?"""
    if value is None or value is NotImplemented or value is Ellipsis:
        return True
    if isinstance(value, (bool, int, float, complex, range_type,
            Markup) + string_types):
        return True
    if isinstance(value, (tuple, list, set, frozenset)):
        for item in value:
            if not has_safe_repr(item):
                return False
        return True
    elif isinstance(value, dict):
        for key, value in iteritems(value):
            if not has_safe_repr(key):
                return False
            if not has_safe_repr(value):
                return False
        return True
    return False

def new_context(environment, template_name, blocks, vars=None,
                shared=None, globals=None, locals=None):
    """Internal helper to for context creation."""
    if vars is None:
        vars = {}
    if shared:
        parent = vars
    else:
        parent = dict(globals or (), **vars)
    if locals:
        # if the parent is shared a copy should be created because
        # we don't want to modify the dict passed
        if shared:
            parent = dict(parent)
        for key, value in iteritems(locals):
            if value is not missing:
                parent[key] = value
    return environment.context_class(environment, parent, template_name,
                                     blocks)

def new_context(environment, template_name, blocks, vars=None,
                shared=None, globals=None, locals=None):
    """Internal helper to for context creation."""
    if vars is None:
        vars = {}
    if shared:
        parent = vars
    else:
        parent = dict(globals or (), **vars)
    if locals:
        # if the parent is shared a copy should be created because
        # we don't want to modify the dict passed
        if shared:
            parent = dict(parent)
        for key, value in iteritems(locals):
            if key[:2] == 'l_' and value is not missing:
                parent[key[2:]] = value
    return Context(environment, parent, template_name, blocks)

def list_templates(self):
        result = []
        for prefix, loader in iteritems(self.mapping):
            for template in loader.list_templates():
                result.append(prefix + self.delimiter + template)
        return result

def new_context(environment, template_name, blocks, vars=None,
                shared=None, globals=None, locals=None):
    """Internal helper to for context creation."""
    if vars is None:
        vars = {}
    if shared:
        parent = vars
    else:
        parent = dict(globals or (), **vars)
    if locals:
        # if the parent is shared a copy should be created because
        # we don't want to modify the dict passed
        if shared:
            parent = dict(parent)
        for key, value in iteritems(locals):
            if key[:2] == 'l_' and value is not missing:
                parent[key[2:]] = value
    return Context(environment, parent, template_name, blocks)

def derived(self, locals=None):
        """Internal helper function to create a derived context.  This is
        used in situations where the system needs a new context in the same
        template that is independent.
        """
        context = new_context(self.environment, self.name, {},
                              self.get_all(), True, None, locals)
        context.eval_ctx = self.eval_ctx
        context.blocks.update((k, list(v)) for k, v in iteritems(self.blocks))
        return context