Indendation problems in python

Indentation is a part of code structure in python.

Indentation problems cause error messages like

IndentationError: unindent does not match any outer indentation level
IndentationError: expected an indented block after ‘for’ statement on line 3

There are many, really many tutorials in the web about this topic. … r_features … tation.asp

Usual problems are:
– various deep levels, e.g. 3 blank or 4 blank deep mixed (use 4 blanks)
– mix of blanks and tabs for indentation.

Thonny is a common IDE, editor for beginners. See
Too see the difference between tabs and blanks, it is good to have ‘highlight tab characters’ enabled in the options.


Then in the thonny editor, tabs are displayed in a special color. Usually a good idea to replace tabs by blanks.


The sample shows two tab in second line.

There are text editor around which allow better visibility of all these invisible characters in a text. Here an example of a blank followed by a tab in second line.


This is from “Notepad++”; good to have such a tool in the toolbox to fix stubborn problems.