Cross platform Python paths for Neovim

init.vim

if (has('nvim'))
    " Path to Python2 and Python3 binaries which are required by some plugins.
    
    " A function that runs the shell `which` command and sanitizes the output.
    function! Which(cmd)
      return substitute(system("which " . a:cmd), "\n", "", "")
    endfunction

    let g:python_host_prog = Which("python2")
    let g:python3_host_prog = Which("python3")
endif