Python中str is not callable問題詳解及解決方法

def check_province_code(province, country):
  num = len(province)
    
  while num <3:
    province = &#39;&#39;.join([str(0),province])
    num = num +1
    
  return country + province

check_province_code('ab', '001')
---------------------------------------------------------------------------
TypeError                 Traceback (most recent call last)
<ipython-input-44-02ec8a351cce> in <module>()
----> 1 check_province_code(&#39;ab&#39;, &#39;001&#39;)
  
<ipython-input-43-12db968aa80a> in check_province_code(province, country)
   3 
   4   while num <3:
----> 5     province = &#39;&#39;.join([str(0),province])
   6     num = num +1
   7 
  
TypeError: &#39;str&#39; object is not callable

>>> str(1233)
---------------------------------------------------------------------------
TypeError                 Traceback (most recent call last)
<ipython-input-45-afcef5460e92> in <module>()
----> 1 str(1233)
  
TypeError: &#39;str&#39; object is not callable