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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 attributes(self):
 """ Return an iterator over this value's attributes. The iterator will yield a string for each attribute. """

        itr = iter(())
        if self.is_function:
            it = ffi.lib.LLVMPY_FunctionAttributesIter(self)
            itr = _AttributeListIterator(it)
        elif self.is_instruction:
            if self.opcode == 'call':
                it = ffi.lib.LLVMPY_CallInstAttributesIter(self)
                itr = _AttributeListIterator(it)
            elif self.opcode == 'invoke':
                it = ffi.lib.LLVMPY_InvokeInstAttributesIter(self)
                itr = _AttributeListIterator(it)
        elif self.is_global:
            it = ffi.lib.LLVMPY_GlobalAttributesIter(self)
            itr = _AttributeSetIterator(it)
        elif self.is_argument:
            it = ffi.lib.LLVMPY_ArgumentAttributesIter(self)
            itr = _AttributeSetIterator(it)
        return itr