When I try to comment out this little code by triple quotation, 
I run into
SyntaxError: (unicode error) 'unicodeescape' codec can't decode bytes in position 29-30: truncated \uXXXX escape

ls_tex = []
ls_tex.append(r'\usepackage{mathtools}')
print(ls_tex)

Basically it is not possible to use r'\u' and comment it out with ''' or """. I think this should not be the case, this is an interpreter error.