func ExampleRecord_Distance() {
	h := strings.Split("MMSI,BaseDateTime,LAT,LON,SOG,COG,Heading,VesselName,IMO,CallSign,VesselType,Status,Length,Width,Draft,Cargo", ",")
	headers := ais.Headers{Fields: h}
	latIndex, _ := headers.Contains("LAT")
	lonIndex, _ := headers.Contains("LON")
	data1 := strings.Split("477307900,2017-12-01T00:00:03,36.90512,-76.32652,0.0,131.0,352.0,FIRST,IMO9739666,VRPJ6,1004,moored,337,,,", ",")
	data2 := strings.Split("477307902,2017-12-01T00:00:03,36.91512,-76.22652,2.3,311.0,182.0,SECOND,IMO9739800,XHYSF,,underway using engines,337,,,", ",")
	rec1 := ais.Record(data1)
	rec2 := ais.Record(data2)
	nm, err := rec1.Distance(rec2, latIndex, lonIndex)
	if err != nil {
		panic(err)
	}
	fmt.Printf("The ships are %.1fnm away from one another.\n", nm)
}
Example demonstrates a simple use of the Distance function.
package ais_test
import (
	"fmt"
	"strings"
	"time"
	"github.com/FATHOM5/ais"
)