code: function(coords){
  			var keys = geolib.getKeys(coords[0]);
  			var elevation = keys.elevation;
  			var rise = Math.abs(coords[coords.length-1][elevation] - coords[0][elevation]);
  			var run = geolib.getPathLength(coords);
  			return Math.floor((rise/run)*100);
  		}
docs: @param      Array [{lat:#lat, lng:#lng, elev:#elev},....]}
  
  @return     Number % grade