Clean up the output when an unknow type is found
Cleaned up output
Use pretty formatting
Better Py2/3 support
Merge remote-tracking branch 'sontek/give_better_error_output'

* sontek/give_better_error_output:
  Better Py2/3 support
  Use pretty formatting
  Cleaned up output
  Clean up the output when an unknow type is found
Flake8.
Try to be as unconfusing as possible since is_type can be called outside validation.