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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_source(self, key, name_spaces=None, default_prefix=''):
 """Generates the dictionary key for the serialized representation based on the instance variable source and a provided key. :param str key: name of the field in model :returns: self.source or key """

        source = self.source or key
        prefix = default_prefix
        if name_spaces and self.name_space and self.name_space in name_spaces:
            prefix = ''.join([name_spaces[self.name_space], ':'])
        return ''.join([prefix, source])