code: def Indentation( logical_line,
                   previous_logical,
                   indent_level,
                   previous_indent_level ):
    
    comment = '' if logical_line else ' (comment)'
    if indent_level % 2:
      code = 'YCM111' if logical_line else 'YCM114'
      message = ' indentation is not a multiple of two spaces' + comment
      yield 0, code + message
    if ( previous_logical.endswith( ':' ) and
         ( indent_level - previous_indent_level != 2 ) ):
      code = 'YCM112' if logical_line else 'YCM115'
      message = ' expected an indented block of {} spaces{}'.format(
        previous_indent_level + 2, comment )
      yield 0, code + message
docs: Use two spaces per indentation level.