Citing from reindent docs:
Change Python (.py) files to use 4-space indents and no hard tab
characters. Also trim excess spaces and tabs from ends of lines, and
remove empty lines at the end of files. Also ensure the last line
ends with a newline.
Citing from PEP 8:
Use 4 spaces per indentation level.
Python 2 code indented with a mixture of tabs and spaces should be
converted to using spaces exclusively.
Don't write string literals that rely on significant trailing
whitespace. Such trailing whitespace is visually indistinguishable
and some editors (or more recently, reindent.py) will trim them.
Also PyLint recommends not to have trailing whitespace on any line.
