<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def check_meta(meta):
 """ Validate meta dict. Raise ValueError if validation fails. """

    if not isinstance(meta, dict):
        raise ValueError("bad metadata - not a dictionary")
    if not isinstance(meta.get("announce"), basestring):
        raise ValueError("bad announce URL - not a string")
    check_info(meta.get("info"))

    return meta