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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 get_broadcast_transactions(coin_symbol='btc', limit=10, api_key=None):
 """ Get a list of broadcast but unconfirmed transactions Similar to bitcoind's getrawmempool method """

    url = make_url(coin_symbol, 'txs')

    params = {}
    if api_key:
        params['token'] = api_key
    if limit:
        params['limit'] = limit

    r = requests.get(url, params=params, verify=True, timeout=TIMEOUT_IN_SECONDS)
    response_dict = get_valid_json(r)

    unconfirmed_txs = []
    for unconfirmed_tx in response_dict:
        unconfirmed_tx['received'] = parser.parse(unconfirmed_tx['received'])
        unconfirmed_txs.append(unconfirmed_tx)
    return unconfirmed_txs