graph

type Edge struct {
	H, T Node
	Cost float64
}

type Graph interface {
	NodeExists(Node) bool
	NodeList() []Node
	Neighbors(Node) []Node
	EdgeBetween(node, neighbour Node) *Edge

	Successors(Node) []Node
	EdgeTo(node, successor Node) *Edge
	Predecessors(Node) []Node

	Cost(*Edge) float64

	NewNode() Node
	AddNode(Node)
	RemoveNode(Node)

	AddDirectedEdge(e *Edge)
	RemoveDirectedEdge(e *Edge)

	Copy() Graph
}

type Node struct {
	Id  int
	Lat float64
	Lng float64
}