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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def check_switch_vendor(old_vendor, name, urls, _depth=0):
 """Check if the project should switch vendors. E.g project pushed on pypi, but changelog on launchpad. :param name: str, name of the project :param urls: set, urls to check. :return: tuple, (str(new vendor name), str(new project name)) """

    if _depth > 3:
        # Protect against recursive things vendors here.
        return ""
    new_name = check_for_launchpad(old_vendor, name, urls)
    if new_name:
        return "launchpad", new_name
    return "", ""