text: var ctx         = require('./$.ctx')
    , call        = require('./$.iter-call')
    , isArrayIter = require('./$.is-array-iter')
    , anObject    = require('./$.an-object')
    , toLength    = require('./$.to-length')
    , getIterFn   = require('./core.get-iterator-method');
  module.exports = function(iterable, entries, fn, that){
    var iterFn = getIterFn(iterable)
      , f      = ctx(fn, that, entries ? 2 : 1)
      , index  = 0
      , length, step, iterator;
    if(typeof iterFn != 'function')throw TypeError(iterable + ' is not iterable!');
    // fast case for arrays with default iterator
    if(isArrayIter(iterFn))for(length = toLength(iterable.length); length > index; index++){
      entries ? f(anObject(step = iterable[index])[0], step[1]) : f(iterable[index]);
    } else for(iterator = iterFn.call(iterable); !(step = iterator.next()).done; ){
      call(iterator, f, step.value, entries);
    }
  };