/*
 copyMap copies a given map.
*/
func copyMap(m, base={}) {
    let ret := base
    for [k, v] in m {
        ret[k] := v
    }
    return ret
}

/*
 max returns the maximum of two numbers.
*/
func max(a, b) {
    if a > b {
        return a
    }
    return b
}

/*
 allNodeKeys returns the keys of all nodes of a certain kind.
*/
func allNodeKeys(part, kind) {
    let ret := []
    let res := db.graphQL("main", "{ {{kind}} { key } }", {"kind" : kind})

    if len(res.data[kind]) > 0 {
        for o in res.data[kind] {
            ret := add(ret, o.key)
        }
    }

    return ret
}

/*
 Create a new list from a given list with all elements that pass
 the test implemented by the provided function.
*/
func filter(list, f) {
    ret := []
    for i in list {
        if f(i) {
            ret := add(ret, i)
        }
    }
    return ret
}