At first, the commands below are almost executed in the normal mode

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delete the content in the end of the file

• from to the end of the file . command :dG

delete the specific code block(function&backers)

If you are in the function or loop , you wilt select by yourself

• delete the code in the {}. command: di{
• delete the code (contain the backers). command: da{

the best way i think

delete the specific lines command: :10,50d

i dont want to code the sheet by hand

delete the current line -> dd delete the next 10 lines -> 10dd

NOTE: the undo way, u to undo the last change