from mapnik import Map, Layer
proj4 = '+proj=tmerc +lat_0=0 +lon_0=-58.5 +k=0.9999 +x_0=304800 +y_0=0 +ellps=clrk66 +units=m +no_defs'
m = Map(256,256,proj4)
lyr = Layer('Name',proj4)