from mapnik import Map, Layer
proj4 = '+proj=cass +lat_0=39.1395087777778 +lon_0=7.50094186111111 +x_0=-0 +y_0=-0 +ellps=bessel +pm=8.921030277777779 +units=m +no_defs'
m = Map(256,256,proj4)
lyr = Layer('Name',proj4)