2 examples : 

• for debug(what) there is a comment: Print debug message if debugging is switched on
  But how can i switch debug  on
• in a line like 
  for node in self.svg.selection.filter(inkex.PathElement)
  i use filter but there is no informations on other filter. Is it possible to use something like not(pathElement) ? I want to modify all element that are not svg path lihe circle, line or polygon.
  Is there a way to find help on this. I'm going on (https://inkscape.gitlab.io/extensions/documentation/source/inkex.elements._selected.html#inkex.elements._selected.ElementList) and find this :
  filter(*types)[source]
  Filter selected elements of the given type, returns a new SelectedElements object
  But nothing about the type and no link.

Is there a more functional way to find help.

I think you can just use the inkex element types so for example Inkex.Rectangle or Inkex.PathElement or Inkex.Circle

The same types you would use to create an element.

filtered_elements = self.svg.selection.filter(inkex.PathElement, inkex.Rectangle)

for element in filtered_elements:
    inkex.errormsg(f'{element.TAG} : {element.get_id()}')
return

Or if you want a list you could use the tags:

for element in selection_list:
    if element.TAG != 'rect' and element.TAG != 'circle' and element.TAG != 'text':
        inkex.errormsg(f'{element.TAG} : {element.get_id()}')

Or just make a custom xpath list:

drawable_elements = self.svg.xpath('//svg:circle | //svg:ellipse | //svg:image | //svg:line | //svg:path | '
                                             '//svg:polygon | //svg:polyline | //svg:rect | //svg:svg | //svg:text | '
                                             '//svg:use')

Thanks that's what I was looking for.

But how can I find all filter types on my own. I don't wanna to ask at every time.

And  how can i switch on debug .

Each section in inkex.elements api reference should give you the correct type class.

However for any object in python you can use this piece of code to return attributes etc:

def get_attributes(self):

    attribute_string = ''
    for att in dir(self):
        try:
            attribute = (att, getattr(self, att))
            attribute_string = attribute_string + str(attribute) + '\n'
        except:
            None
            
    return attribute_string

If you try for the inkex module: 
    
attributes_string = get_attributes(inkex)

then just get lines which contain 'elements._'

for line in attributes_string.splitlines():
    if 'elements._' in line:
        inkex.errormsg(line)

Gives:

('Anchor', <class 'inkex.elements._groups.Anchor'>)
('BaseElement', <class 'inkex.elements._base.BaseElement'>)
('Circle', <class 'inkex.elements._polygons.Circle'>)
('ClipPath', <class 'inkex.elements._groups.ClipPath'>)
('Defs', <class 'inkex.elements._meta.Defs'>)
('Desc', <class 'inkex.elements._meta.Desc'>)
('Ellipse', <class 'inkex.elements._polygons.Ellipse'>)
('Filter', <class 'inkex.elements._filters.Filter'>)
('FlowDiv', <class 'inkex.elements._text.FlowDiv'>)
('FlowPara', <class 'inkex.elements._text.FlowPara'>)
('FlowRegion', <class 'inkex.elements._text.FlowRegion'>)
('FlowRoot', <class 'inkex.elements._text.FlowRoot'>)
('FlowSpan', <class 'inkex.elements._text.FlowSpan'>)
('FontFace', <class 'inkex.elements._text.FontFace'>)
('ForeignObject', <class 'inkex.elements._meta.ForeignObject'>)
('Glyph', <class 'inkex.elements._text.Glyph'>)
('Gradient', <class 'inkex.elements._filters.Gradient'>)
('Grid', <class 'inkex.elements._meta.Grid'>)
('Group', <class 'inkex.elements._groups.Group'>)
('Guide', <class 'inkex.elements._meta.Guide'>)
('Image', <class 'inkex.elements._image.Image'>)
('Layer', <class 'inkex.elements._groups.Layer'>)
('Line', <class 'inkex.elements._polygons.Line'>)
('LinearGradient', <class 'inkex.elements._filters.LinearGradient'>)
('Marker', <class 'inkex.elements._groups.Marker'>)
('Mask', <class 'inkex.elements._groups.Mask'>)
('MeshGradient', <class 'inkex.elements._filters.MeshGradient'>)
('MeshPatch', <class 'inkex.elements._filters.MeshPatch'>)
('MeshRow', <class 'inkex.elements._filters.MeshRow'>)
('Metadata', <class 'inkex.elements._meta.Metadata'>)
('MissingGlyph', <class 'inkex.elements._text.MissingGlyph'>)
('NamedView', <class 'inkex.elements._meta.NamedView'>)
('Page', <class 'inkex.elements._meta.Page'>)
('PathEffect', <class 'inkex.elements._filters.PathEffect'>)
('PathElement', <class 'inkex.elements._polygons.PathElement'>)
('Pattern', <class 'inkex.elements._filters.Pattern'>)
('Polygon', <class 'inkex.elements._polygons.Polygon'>)
('Polyline', <class 'inkex.elements._polygons.Polyline'>)
('RadialGradient', <class 'inkex.elements._filters.RadialGradient'>)
('Rectangle', <class 'inkex.elements._polygons.Rectangle'>)
('SVGfont', <class 'inkex.elements._text.SVGfont'>)
('Script', <class 'inkex.elements._meta.Script'>)
('ShapeElement', <class 'inkex.elements._base.ShapeElement'>)
('Stop', <class 'inkex.elements._filters.Stop'>)
('StyleElement', <class 'inkex.elements._meta.StyleElement'>)
('SvgDocumentElement', <class 'inkex.elements._svg.SvgDocumentElement'>)
('Switch', <class 'inkex.elements._meta.Switch'>)
('Symbol', <class 'inkex.elements._use.Symbol'>)
('TextElement', <class 'inkex.elements._text.TextElement'>)
('TextPath', <class 'inkex.elements._text.TextPath'>)
('Title', <class 'inkex.elements._meta.Title'>)
('Tspan', <class 'inkex.elements._text.Tspan'>)
('Use', <class 'inkex.elements._use.Use'>)

Thank's a lot.