Wasting time for nothing

Today I was developing a new project using Django when I got the following error message:

File "/home/marcio/prj/py/ProjectManager/partlist/models.py", line 29
  friends = models.ManyToManyField("self", related_name='component_friends', symmetrical=False)
                                                                                              ^
IndentationError: unindent does not match any outer indentation level
marcio@mr02:~/prj/py/ProjectManager$

That error was caused by me because I unintentionally mixed tabs and spaces. I know I can't mix them but I did it and I wasted some precious time trying to figure out what was happening.

So if you see this error you will already know the solution. ;)