code: function writeScriptLockedPayToPubKeyHash(address, locktime, buffer, offset) {
      let locktime_buffer = Buffer.from(locktime, 'hex');
      offset = buffer.writeUInt8(27 + locktime_buffer.length, offset); //Script length
      offset = buffer.writeUInt8(locktime_buffer.length, offset); //Length of locktime
      offset += locktime_buffer.copy(buffer, offset);
      offset = buffer.writeUInt8(OPS.OP_NUMEQUALVERIFY, offset);
      offset = buffer.writeUInt8(OPS.OP_DUP, offset);
      offset = buffer.writeUInt8(OPS.OP_HASH160, offset);
      //Write previous output address
      offset = buffer.writeUInt8(20, offset); //Address length
      offset += Buffer.from(base58check.decode(address, 'hex').data, 'hex').copy(buffer, offset);
      offset = buffer.writeUInt8(OPS.OP_EQUALVERIFY, offset);
      offset = buffer.writeUInt8(OPS.OP_CHECKSIG, offset);
      return offset;
  }
docs: Write locked p2pkh to the given buffer.
  @param {String} address
  @param {String} locktime little endian hex
  @param {Buffer} buffer
  @param {Number} offset
  @returns {Number} new offset