The UNWIND keyword is no longer used

This part could be removed:

Lines 118 to 120 in 364384b

    
           	\item $\mathsf{UNWIND}$ unnests a list, \ie produces a set of one-tuples. For  
        
           	example, $\mathsf{UNWIND} [1, 2, 3]$ results in $ \{ \tuple{1}, \tuple{2},  
        
           	\tuple{3} \} $.

	\item $\mathsf{UNWIND}$ unnests a list, \ie produces a set of one-tuples. For
	example, $\mathsf{UNWIND} [1, 2, 3]$ results in $ \{ \tuple{1}, \tuple{2},
	\tuple{3} \} $.