<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _validate_authority_uri_abs_path(host, path):
 """Ensure that path in URL with authority starts with a leading slash. Raise ValueError if not. """

        if len(host) > 0 and len(path) > 0 and not path.startswith("/"):
            raise ValueError(
                "Path in a URL with authority " "should start with a slash ('/') if set"
            )