ValueError：需要超过0个值来解压缩Python中的错误

Today I tried to execute the following command in Linux, I want to test the Streaming interface in hadoop,

 cat test.txt|php wc_mapper.php|python Reducer.py

an error happened:

"Traceback (most recent call last):
 File "Reducer.py", line 7, in <module>
word,count = line.split()   
ValueError: need more than 0 values to unpack
"

the content of test.txt is as follows:

hello world
hello world
hello world

the content of wc_mapper.php which is written by PHP is

#!/usr/bin/php
<?php
error_reporting(E_ALL ^ E_NOTICE);
$word2count = array();
while (($line = fgets(STDIN)) !== false) {
      $line = trim($line);
      $words = preg_split('/\W/', $line, 0, PREG_SPLIT_NO_EMPTY);
      foreach ($words as $word) {
                echo $word, chr(9), "1", PHP_EOL;
      }
}
?>

and the content of Reducer.py which is written by Python is

#!/usr/bin/python
from operator import itemgetter
import sys
word2count = {}
for line in sys.stdin:
   line = line.strip()
   word,count = line.split()
   try:
      count = int(count)
      word2count[word] = word2count.get(word, 0) + count
   except ValueError:
      pass

sorted_word2count = sorted(word2count.items(), key=itemgetter(0))
for word,count in sorted_word2count:
   print '%s\t%s'%(word,count)

who knows the reason of the error, how to fix this issue? when I execute the first part command

cat test.txt|php wc_mapper.php|sort

, I got the following output:

hello   1
hello   1
hello   1
world   1
world   1
world   1

the first line is null, but it occupy one line.

Provide delimiter in split() function

   try:    
        word,count = line.split(" ") 
   except:
        print("Error")

I have put single space as delimiter. you can change accordingly.