function iterFirst( iterator ) {
	var v;
	if ( !isIteratorLike( iterator ) ) {
		throw new TypeError( format( 'invalid argument. Must provide an iterator. Value: `%s`.', iterator ) );
	}
	v = iterator.next();
	if ( v.done ) {
		return;
	}
	return v.value;
}
Returns the first iterated value.

@param {Iterator} iterator - input iterator
@throws {TypeError} must provide an iterator
@returns {*} first iterated value

@example
var array2iterator = require( '@stdlib/array/to-iterator' );

var it = array2iterator( [ 1, 0, 0, 0, 0 ] );

var v = iterFirst( it );
// returns 1