Fix coc tab bug

.vimrc

@@ -114,6 +114,11 @@ inoremap <silent><expr> <TAB>
       \ coc#refresh()
 inoremap <expr><S-TAB> pumvisible() ? "\<C-p>" : "\<C-h>"
 
+function! s:check_back_space() abort
+      let col = col('.') - 1
+        return !col || getline('.')[col - 1]  =~# '\s'
+    endfunction
+                     
 "Coc vimlsp Highlighting
 let g:markdown_fenced_languages = [
       \ 'vim',