For new projects, spaces-only are strongly recommended over tabs.  Most
    editors have features that make this easy to do.

def tabs_obsolete(physical_line):
    """
    For new projects, spaces-only are strongly recommended over tabs.  Most
    editors have features that make this easy to do.
    """
    indent = indent_match(physical_line).group(1)
    if indent.count('\t'):
        return indent.index('\t'), "W191 indentation contains tabs"