text: #!/usr/bin/env python3
  __author__ = "Christopher Perry"
  __email__ = "ozbonus@gmail.com"
  
  
  """
  Clean up the words
  
  Challenge Description:
  
  You have a list of words. Letters of these words are mixed with extra
  symbols, so it is hard to define the beginning and end of each word.
  Write a program that will clean up the words from extra numbers and
  symbols.
  
  Input sample:
  
  The first argument is a path to a file. Each line includes a test case with a list of words: letters are both lowercase and uppercase, and are mixed with extra symbols.
  
  For example:
  
  (--9Hello----World...--)
  Can 0$9 ---you~
  13What213are;11you-123+138doing7
  
  Output sample:
  
  Print the cleaned up words separated by spaces in lowercase letters.
  
  For example:
  
  hello world
  can you
  what are you doing
  
  Constraints:
  
  1. Print the words separated by spaces in lowercase letters.
  2. The length of a test case together with extra symbols can be in a
     range from 10 to 100 symbols.
  3. The number of test cases is 40.
  
  """
  
  import sys
  import re
  
  with open(sys.argv[1], "r") as cases:
      for line in cases:
          string = re.split("[^a-zA-Z]*", line)
          string[:] = [item.lower() for item in string if item != ""]
          print(" ".join(string))
  