from mapnik import Map, Layer
proj4 = '+proj=tmerc +lat_0=-17 +lon_0=178.75 +k=0.99985 +x_0=2000000 +y_0=4000000 +ellps=WGS72 +units=m +no_defs'
m = Map(256,256,proj4)
lyr = Layer('Name',proj4)