minor formating update. Ref #2700

xonsh/platform.py

@@ -145,11 +145,13 @@ def ptk_above_min_supported():
     minimum_required_ptk_version = (1, 0)
     return ptk_version_info()[:2] >= minimum_required_ptk_version
 
+
 @functools.lru_cache(1)
 def ptk_below_max_supported():
     ptk_max_version_cutoff = (2, 0)
     return ptk_version_info()[:2] < ptk_max_version_cutoff
 
+
 @functools.lru_cache(1)
 def best_shell_type():
     if ON_WINDOWS or has_prompt_toolkit():

xonsh/shell.py

@@ -142,7 +142,7 @@ class Shell(object):
                               'supported. Please see Github PR #2570 for '
                               'latest status. To use prompt-toolkit now you '
                               'can downgrade to version 1.x with\n'
-                              'pip install "prompt_toolkit<2"\n'
+                              'xpip install "prompt_toolkit<2"\n'
                               'Starting xonsh with readline shell instead.')
                 shell_type = 'readline'
         self.shell_type = env['SHELL_TYPE'] = shell_type