def add_pem_headfoot(public_key):
    """
    Return string, representing PEM text for a public key

    Keyword Parameters:
    public_key  -- String, representing the public key text

    >>> add_pem_headfoot('foo')
    '-----BEGIN PUBLIC KEY-----\\nfoo\\n-----END PUBLIC KEY-----'
    """
    preamble = "-----BEGIN PUBLIC KEY-----\n"
    suffix = "\n-----END PUBLIC KEY-----"
    return preamble+public_key+suffix