go to definition doesn't work for me.

[purpleP]

You can try to replicate this opening refactoring.py from this repo and pressing g
It finds definitions if they in the current file however.
Here is my full vimrc file in case this is important.

set nocompatible              " be iMproved, required
filetype off                  " required

call plug#begin('~/.vim/plugged')

Plug 'Valloric/YouCompleteMe'
Plug 'scrooloose/nerdtree', {'on': 'NERDTreeToggle'}
Plug 'Raimondi/delimitMate'
Plug 'scrooloose/syntastic'
Plug 'scrooloose/nerdcommenter'
Plug 'eagletmt/neco-ghc', {'for': 'haskel'}
"Plug 'atweiden/vim-dragvisuals'
"Plug 'vim-scripts/Align'
"Plug 'vim-scripts/vis
Plug 'sheerun/vim-polyglot'
Plug 'tpope/vim-unimpaired'
Plug 'easymotion/vim-easymotion'
Plug 'hdima/python-syntax', {'for': 'python'}
Plug 'jeffkreeftmeijer/vim-numbertoggle'
"Plug 'powerline/powerline'
Plug 'AndrewRadev/sideways.vim'
Plug 'davidhalter/jedi-vim'
Plug 'SirVer/ultisnips' | Plug 'honza/vim-snippets'
Plug 'tpope/vim-surround'
Plug 'ctrlpvim/ctrlp.vim' |  Plug 'FelikZ/ctrlp-py-matcher'
Plug 'junegunn/vim-easy-align'
"Plug 'klen/python-mode', {'for': 'python'}

call plug#end()

" Start interactive EasyAlign in visual mode (e.g. vipga)
xmap ga <Plug>(EasyAlign)
"
" " Start interactive EasyAlign for a motion/text object (e.g. gaip)
nmap ga <Plug>(EasyAlign)


filetype plugin indent on    " required
set tabstop=4
set shiftwidth=4
set expandtab
" remap colon to semicolon in norman and visual mode, but not in insert mode
nnoremap ; :
nnoremap : ;
vnoremap ; :
vnoremap : ;

nnoremap <c-h> :SidewaysLeft<cr>
nnoremap <c-l> :SidewaysRight<cr>

" Bubble single lines
nmap <C-K> [e
nmap <C-J> ]e
vmap <C-Up> [egv
" " Bubble multiple lines
vmap <C-Down> ]egv

" Enable folding
set foldmethod=indent
set foldlevel=99


set background=dark
let python_highlight_builtin_objs = 1
let python_highlight_builtin_funcs = 1
let python_highlight_all = 1
" backspace can delete everyting
set backspace=indent,eol,start

autocmd FileType make setlocal ts=8 sts=8 sw=8 noexpandtab
autocmd FileType yaml setlocal ts=2 sts=2 sw=2 expandtab
autocmd FileType html setlocal ts=2 sts=2 sw=2 expandtab
autocmd FileType css setlocal ts=2 sts=2 sw=2 expandtab

runtime plugin/dragvisuals.vim

" Disable haskell-vim omnifunc
let g:haskellmode_completion_ghc = 0
autocmd FileType haskell setlocal omnifunc=necoghc#omnifunc
autocmd CursorMovedI * if pumvisible() == 0|pclose|endif
autocmd InsertLeave * if pumvisible() == 0|pclose|endif
set statusline+=%#warningmsg#
set statusline+=%{SyntasticStatuslineFlag()}
set statusline+=%*

let g:syntastic_always_populate_loc_list = 1
let g:syntastic_auto_loc_list = 1
let g:syntastic_check_on_open = 1
let g:syntastic_check_on_wq = 0
 "mappings for dragvisuals plugin
"vmap  <expr>  <LEFT>   DVB_Drag('left')
"vmap  <expr>  <RIGHT>  DVB_Drag('right')
"vmap  <expr>  <DOWN>   DVB_Drag('down')
"vmap  <expr>  <UP>     DVB_Drag('up')
"vmap  <expr>  D        DVB_Duplicate()

"nnoremap <leader>|cc :call NERDComment(0,"toggle")<CR>
"vnoremap <leader>|cc :call NERDComment(0,"toggle")<CR>

let g:syntastic_always_populate_loc_list = 1
let g:syntastic_auto_loc_list = 1
let g:syntastic_check_on_open = 1
let g:syntastic_check_on_wq = 0

let g:ycm_semantic_triggers = {'haskell' : ['.']}
let mapleader = "\<Space>"
syntax enable
set background=dark
colorscheme solarized
set wildmenu
set number
if !has('nvim')
    set encoding=utf-8
endif

function! g:UltiSnips_Complete()
    call UltiSnips#ExpandSnippet()
    if g:ulti_expand_res == 0
        if pumvisible()
            return "\<C-n>"
        else
            call UltiSnips#JumpForwards()
            if g:ulti_jump_forwards_res == 0
                return "\<TAB>"
            endif
        endif
    endif
    return ""
endfunction

function! g:UltiSnips_Reverse()
    call UltiSnips#JumpBackwards()
    if g:ulti_jump_backwards_res == 0
        return "\<C-P>"
    endif

    return ""
endfunction


if !exists("g:UltiSnipsJumpForwardTrigger")
    let g:UltiSnipsJumpForwardTrigger = "<tab>"
endif

if !exists("g:UltiSnipsJumpBackwardTrigger")
    let g:UltiSnipsJumpBackwardTrigger="<s-tab>"
endif

au InsertEnter * exec "inoremap <silent> " . g:UltiSnipsExpandTrigger     . " <C-R>=g:UltiSnips_Complete()<cr>"

if !has('nvim')
    set smartcase
    set hlsearch      " highlight search terms
    set incsearch     " show search matches as you type
endif

if has('nvim')
    tnoremap <Esc> <C-\><C-n>
endif

nnoremap <F3> :noh<CR>

"python from powerline.vim import setup as powerline_setup
"python powerline_setup()
"python del powerline_setup
nnoremap <leader>f za
"nnoremap <leader>g :YcmCompleter GoToDefinitionElseDeclaration<CR>
au FileType python setlocal formatprg=autopep8\ -
"set laststatus=2
cmap w!! w !sudo tee % >/dev/null

if has("autocmd")
    autocmd bufwritepost .vimrc source $MYVIMRC
endif

[purpleP]

I've also find that in the same file it goes to definition of script.goto_assignment succesfully. So from that I can assume that parser simply can't find definitions if they more than one level deep in object hierarchy.

[davidhalter]

I cannot seem to reproduce this. So you're pressing leader g and it doesn't work? But where exactly?