code: function(coords){
  			var keys = geolib.getKeys(coords[0]);
  			var elevation = keys.elevation;
  			var gain = 0;
  			var loss = 0;
  			for(var i = 0; i < coords.length - 1; i++){
  				var deltaElev = coords[i][elevation] - coords[i + 1][elevation];
  				if (deltaElev > 0) {
  					loss += deltaElev;
  				} else {
  					gain += Math.abs(deltaElev);
  				}
  			}
  			return {
  				"gain": gain,
  				"loss": loss
  			};
  		}
docs: @param      Array [{lat:#lat, lng:#lng, elev:#elev},....]}
  
  @return     Object {gain:#gain, loss:#loss}