new_contents: from pylayers.gis.layout import *
  import pylayers.util.geomutil as geu
  L=Layout('WHERE1.ini')
  L.build()
  
  lc = [(n,L.Gt.node[n]['polyg'].isconvex()) for n in L.Gt.nodes()]
  cnc = [n for n in L.Gt.nodes() if not L.Gt.node[n]['polyg'].isconvex()]
  fig,ax=L.showG('st',labels=True)
  for cy,c in lc:
      if c:
          print cy,  
          fig,ax= L.Gt.node[cy]['polyg'].plot(color='blue',alpha=0.5,fig=fig,ax=ax)
      else:
          fig, ax = L.Gt.node[cy]['polyg'].plot(color='red', alpha=0.5,fig=fig,ax=ax)
subject: Add test convex in gis