<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def save_indent(token_class, start=False):
 """Save a possible indentation level."""

        def callback(lexer, match, context):
            text = match.group()
            extra = ''
            if start:
                context.next_indent = len(text)
                if context.next_indent < context.indent:
                    while context.next_indent < context.indent:
                        context.indent = context.indent_stack.pop()
                    if context.next_indent > context.indent:
                        extra = text[context.indent:]
                        text = text[:context.indent]
            else:
                context.next_indent += len(text)
            if text:
                yield match.start(), token_class, text
            if extra:
                yield match.start()+len(text), token_class.Error, extra
            context.pos = match.end()
        return callback