from mapnik import Map, Layer
proj4 = '+proj=longlat +a=6377276.345 +b=6356075.41314024 +towgs84=204.64,834.74,293.8,0.0,0.0,0.0,0.0 +no_defs'
m = Map(256,256,proj4)
lyr = Layer('Name',proj4)