Utility functions on 64-bit unsigned integers
public let maximumValue : Nat64
public let toNat : Nat64 -> Nat
public let fromNat : Nat -> Nat64
public func fromNat32(x : Nat32) : Nat64
public func toNat32(x : Nat64) : Nat32
public let fromIntWrap : Int -> Nat64
public func toText(x : Nat64) : Text
public func bittest(x : Nat64, p : Nat) : Bool