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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_group_index(self, data):
 """Get the next groups style's starting line index :param data: string to parse :returns: the index if found else -1 """

        idx = -1
        li = self.get_group_line(data)
        if li != -1:
            idx = 0
            for line in data.splitlines()[:li]:
                idx += len(line) + len('\n')
        return idx