A BIP65 absolute lock-time encoding library.
let bip65 = require('bip65')
bip65.encode({ utc: 102 })
// => TypeError: Expected Number utc >= 500000000
bip65.encode({ blocks: 1517448381 })
// => TypeError: Expected Number Blocks < 500000000
bip65.encode({ blocks: 54 })
// => 0x00000036
bip65.encode({ blocks: 200 })
// => 0x000000c8
bip65.decode(0x00000036)
// => { blocks: 54 }