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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_repository_existence(params):
 """Check repository existence. :param argparse.Namespace params: parameters """

    repodir = os.path.join(params.outdir, params.name)
    if os.path.isdir(repodir):
        raise Conflict(
            'Package repository "{0}" has already exists.'.format(repodir))