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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 decode_privkey_hex(privkey_hex):
 """ Decode a private key for ecdsa signature """

    if not isinstance(privkey_hex, (str, unicode)):
        raise ValueError("private key is not a string")

    # force uncompressed
    priv = str(privkey_hex)
    if len(priv) > 64:
        if priv[-2:] != '01':
            raise ValueError("private key does not end in '01'")

        priv = priv[:64]

    pk_i = int(priv, 16)
    return pk_i