title: Python:how to input the file name in python
body: <p>im very new to python.
  when I do <code>fileofname = "a2.txt"</code>
  then i can run my code without any problem
  However,when I do <code>fileofname = raw_input("enter the file name:")</code>
  then i type "a2.txt"
  and it raises a <code>"UnboundLocalError: local variable 'line' referenced before assignment"</code></p>
  
  <p>Can someone help me??</p>