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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_fido_dollar(self, account_number, number):
 """Get current Fido dollar balance."""

        # Prepare data
        data = json.dumps({"fidoDollarBalanceFormList":
                           [{"phoneNumber": number,
                             "accountNumber": account_number}]})
        # Prepare headers
        headers_json = self._headers.copy()
        headers_json["Content-Type"] = "application/json;charset=UTF-8"
        # Http request
        try:
            raw_res = yield from self._session.post(FIDO_DOLLAR_URL,
                                                    data=data,
                                                    headers=headers_json,
                                                    timeout=self._timeout)
        except OSError:
            raise PyFidoError("Can not get fido dollar")
        # Get fido dollar
        try:
            json_content = yield from raw_res.json()
            fido_dollar_str = json_content\
                        .get("fidoDollarBalanceInfoList", [{}])[0]\
                        .get("fidoDollarBalance")
        except (OSError, ValueError):
            raise PyFidoError("Can not get fido dollar as json")
        if fido_dollar_str is None:
            raise PyFidoError("Can not get fido dollar")
        # Casting to float
        try:
            fido_dollar = float(fido_dollar_str)
        except ValueError:
            raise PyFidoError("Can not get fido dollar")

        return fido_dollar