I need to integrate V.clean functionality of Grass in a script python. this functionnality is accessible in Qgis (Processing->tools). I found that I should use Grass API but I don't know the code syntax, Please give me examples of use of the Grass API functionalities in a Python script, especially the v.clean function
v.cleanfunction in QGIS, you should see 3 tabs: "Parameters", "Log", "Help". Click "Help" and scroll near the bottom and find the heading 'EXAMPLES'. Here you can see how the syntax should be used.