worldpop(opts, cb)

Computes the total population within the given polygon.

parameter	type	description
opts		Options: max_zoom, min_zoom {(string|ReadableStream<Feature>)} source - A GeoJSON Feature stream or Tilelive uri for the tiled population data, where each feature represents an area of constant population density. {function} density - A function that accepts a feature from source and returns the population density for that feature. {Feature<Polygon>} polygon - The polygon whose interior population we want. {function} progress - A progress callback, called periodically with the current state of {totalPopulation, totalArea, polygonArea}. (You can estimate % complete with totalArea/polygonArea.) {Number} progressFrequency - Frequency (in # of features) of progress callback.
cb		completion callback, called with {totalPopulation, totalArea, polygonArea}.