old_contents: #!/usr/bin/env python
  
  def guardSymbol(fileName):
  	return fileName.upper().replace('.', '_')
  
  def isHeaderFile(fileName):
  	return fileName.endswith('.h') or fileName.endswith('.hpp')
  
new_contents: #!/usr/bin/env python
  
  def guardSymbol(fileName):
  	'''The expected include guard symbol for a given file.
  
  	Returns an include guard symbol as a string.
  	fileName is the name of the file being guarded,
  	and does not include any directory names.
  	'''
  	return fileName.upper().replace('.', '_')
  
  def isHeaderFile(fileName):
  	'''Returns true if the given file is identified as a C/C++ header file.'''
  	return fileName.endswith('.h') or fileName.endswith('.hpp')
  
subject: Add docstrings to crule.py