tab a block code

vim

To adjust the indent on three lines:

Put the cursor anywhere in the first line.
Press V then jj to visually select the three lines.
Press > to indent (shift text one 'shiftwidth' to the right), or press < to shift left.
Press . to repeat the indent, or u to undo if you have shifted too far.
Type gv if you want to reselect the lines (not needed).

If you’re copying blocks of text around and need to align the indent of a block in its new location, 
use ]p instead of just p. This aligns the pasted block with the surrounding text.