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  Table corresponding to the abstract syntax tree 
0,	 name: 2	 left:-1	 right:-1
1,	 name: x1	 left:-1	 right:-1
2,	 name: cos	 left:1	 right:-1
3,	 name: *	 left:0	 right:2
4,	 name: x2	 left:-1	 right:-1
5,	 name: x1	 left:-1	 right:-1
6,	 name: +	 left:4	 right:5
7,	 name: sin	 left:6	 right:-1
8,	 name: *	 left:3	 right:7
9,	 name: 1	 left:-1	 right:-1
10,	 name: +	 left:8	 right:9
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