In the middle of a line, Press
v and select multiple lines.
How to yank the word at current cursor from all selected lines and add spaces if the word is shorter than the longest one to make copied columns aligned.
For example, current cursor is in the beginning of second data_out from first line.
Please note below example is in the middle of a file.
... data_out => data_out, read => read, write => write, full => full, notempty => notempty, ...
After "copy" I can paste below columns.