implement _seek instead of seek

iterator.js

@@ -13,18 +13,9 @@ function Iterator (db, options) {
 
 util.inherits(Iterator, AbstractIterator)
 
-Iterator.prototype.seek = function (target) {
-  if (this._ended) {
-    throw new Error('cannot call seek() after end()')
-  }
-  if (this._nexting) {
-    throw new Error('cannot call seek() before next() has completed')
-  }
-  if (typeof target !== 'string' && !Buffer.isBuffer(target)) {
-    throw new Error('seek() requires a string or buffer key')
-  }
+Iterator.prototype._seek = function (target) {
   if (target.length === 0) {
-    throw new Error('cannot seek() to an empty key')
+    throw new Error('cannot seek() to an empty target')
   }
 
   this.cache = null

test/iterator-test.js

@@ -3,21 +3,13 @@ const iota = require('iota-array')
 const lexi = require('lexicographic-integer')
 const util = require('util')
 
-make('iterator throws if key is not a string or buffer', function (db, t, done) {
-  var keys = [null, undefined, 1, true, false]
-  var pending = keys.length
+make('iterator#seek throws if target is empty', function (db, t, done) {
+  var targets = [null, undefined, '', Buffer.alloc(0), []]
+  var pending = targets.length
 
-  keys.forEach(function (key) {
-    var error
+  targets.forEach(function (target) {
     var ite = db.iterator()
-
-    try {
-      ite.seek(key)
-    } catch (e) {
-      error = e
-    }
-
-    t.ok(error, 'had error from seek()')
+    t.throws(ite.seek.bind(ite, target), /Error: cannot seek\(\) to an empty target/)
     ite.end(end)
   })