<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def subscriptgroup_handle(tokens):
 """Process subscriptgroups."""

    internal_assert(0 < len(tokens) <= 3, "invalid slice args", tokens)
    args = []
    for arg in tokens:
        if not arg:
            arg = "None"
        args.append(arg)
    if len(args) == 1:
        return args[0]
    else:
        return "_coconut.slice(" + ", ".join(args) + ")"