vim autotag.vim

http://www.vim.org/scripts/script.php?script_id=1343

place autotag.vim under you ~/.vim/plugin/

touch a file tags under the working folder, or the filename you set up in .vimrc
via

let g:autotagTagsFile="your_tags_file_name"


modify your code,

try

# move the cursor at the function want to lookup

Ctrl + ]

# back to edit
Ctrl + t



Good luck