I have script including multiple commands. How can I group commands to run together. i.e.

 #!/bin/bash
 command #1
 command #2
 command #3
 command #4
 command #5
 command #6
 command #7
 command #8
 command #9
 command #10
how can I run every 3 commands to gether? I tried:

 #!/bin/bash
 {
 command #1
 command #2
 command #3
 } & 
 { 
 command #4
 command #5
 command #6
 } & 
 {
 command #7
 command #8
 command #9
 }&
 command #10

But this didn't work properly! Any advice is highly appreciated