How to setup a vim plugin using python 2 or python 3

PythonVimPluginExample.vim

" Basic example of using Python with vim 

" This is basic vim plugin boilerplate
let s:save_cpo = &cpo
set cpo&vim

function! s:UsingPython3()
  if has('python3')
    return 1
  endif
  return 0
endfunction

" Prefer py3
let s:using_python3 = s:UsingPython3()
let s:python_until_eof = s:using_python3 ? "python3 << EOF" : "python << EOF"
let s:python_command = s:using_python3 ? "py3 " : "py "

let s:path = fnamemodify(expand('<sfile>:p:h'), ':h')

" Setup some autocmds
autocmd BufWritePost * call s:OnBufWritePost()
autocmd CursorMoved * call s:OnCursorMoved()
autocmd CursorMovedI * call s:OnCursorMovedI()

" Run some python
function! s:Pyeval( eval_string )
  if s:using_python3
    return py3eval( a:eval_string )
  endif
  return pyeval( a:eval_string )
endfunction

function! s:SetUpPython() abort
  exec s:python_until_eof
import vim
import os
print("Setting up python...")

# Directory of the plugin
plugin_dir  = vim.eval('s:path')
# Add the subdir of the plugin, python
sys.path.insert(0, os.path.join(plugin_dir, 'python'))
Start()

vim.command('return 1')
EOF
endfunction

function! s:OnCursorMovedI()
endfunction

function! s:OnCursorMoved()
endfunction

function! s:OnBufWritePost()
endfunction

echom "Path " . s:path
if s:SetUpPython() != 1
  echom "Setting up python failed..."
endif

" This is basic vim plugin boilerplate
let &cpo = s:save_cpo
unlet s:save_cpo