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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_size_for_density(self, size, target_density):
 """ Return the new image size for the target density """

        current_size = size
        current_density = DENSITY_MAP[self.source_density]
        target_density = DENSITY_MAP[target_density]

        return int(current_size * (target_density / current_density))