Split up the flake8 and ansible-lint handlers

autoload/ale/python.vim

@@ -9,6 +9,26 @@ let g:ale_virtualenv_dir_names = get(g:, 'ale_virtualenv_dir_names', [
 \   'virtualenv',
 \])
 
+" Given a buffer number and a command name, find the path to the executable.
+" First search on a virtualenv for Python, if nothing is found, try the global
+" command. Returns an empty string if cannot find the executable
+function! ale#python#GetExecutable(buffer, cmd_name) abort
+    let l:virtualenv = ale#python#FindVirtualenv(a:buffer)
+
+    if !empty(l:virtualenv)
+        let l:ve_executable = l:virtualenv . '/bin/' . a:cmd_name
+
+        if executable(l:ve_executable)
+            return l:ve_executable
+        endif
+    endif
+
+    if executable(a:cmd_name)
+        return a:cmd_name
+    endif
+
+    return ''
+endfunction
 
 " Given a buffer number, find the project root directory for Python.
 " The root directory is defined as the first directory found while searching