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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 _vector_layers(self):
 """Return a list of vector layers available. :return: List of vector layers available in the geopackage. :rtype: list .. versionadded:: 4.0 """

        layers = []
        vector_datasource = self.vector_driver.Open(
            self.uri.absoluteFilePath())
        if vector_datasource:
            for i in range(vector_datasource.GetLayerCount()):
                layers.append(vector_datasource.GetLayer(i).GetName())
        return layers