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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 send(self, to, amount, from_address=None, fee=None):
 """Send bitcoin from your wallet to a single address. :param str to: recipient bitcoin address :param int amount: amount to send (in satoshi) :param str from_address: specific address to send from (optional) :param int fee: transaction fee in satoshi. Must be greater than the default fee (optional). :return: an instance of :class:`PaymentResponse` class """

        
        recipient = {to: amount}
        return self.send_many(recipient, from_address, fee)