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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 reliability_curve(self):
 """ Calculates the reliability diagram statistics. The key columns are Bin_Start and Positive_Relative_Freq Returns: pandas.DataFrame """

        total = self.frequencies["Total_Freq"].sum()
        curve = pd.DataFrame(columns=["Bin_Start", "Bin_End", "Bin_Center",
                                      "Positive_Relative_Freq", "Total_Relative_Freq"])
        curve["Bin_Start"] = self.thresholds[:-1]
        curve["Bin_End"] = self.thresholds[1:]
        curve["Bin_Center"] = 0.5 * (self.thresholds[:-1] + self.thresholds[1:])
        curve["Positive_Relative_Freq"] = self.frequencies["Positive_Freq"] / self.frequencies["Total_Freq"]
        curve["Total_Relative_Freq"] = self.frequencies["Total_Freq"] / total
        return curve