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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_nested_blocks_spec(self):
 """ Converts allowed_nested_blocks items to NestedXBlockSpec to provide common interface """

        return [
            block_spec if isinstance(block_spec, NestedXBlockSpec) else NestedXBlockSpec(block_spec)
            for block_spec in self.allowed_nested_blocks
        ]