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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 gen_keys(keysize=2048):
    '''
    Generate Salt minion keys and return them as PEM file strings
    '''
    # Mandate that keys are at least 2048 in size
    if keysize < 2048:
        keysize = 2048
    tdir = tempfile.mkdtemp()

    salt.crypt.gen_keys(tdir, 'minion', keysize)
    priv_path = os.path.join(tdir, 'minion.pem')
    pub_path = os.path.join(tdir, 'minion.pub')
    with salt.utils.files.fopen(priv_path) as fp_:
        priv = salt.utils.stringutils.to_unicode(fp_.read())
    with salt.utils.files.fopen(pub_path) as fp_:
        pub = salt.utils.stringutils.to_unicode(fp_.read())
    shutil.rmtree(tdir)
    return priv, pub