old_contents: 
  from IPython.core.magic import (Magics, magics_class, cell_magic)
  from IPython.core.magic_arguments import (argument, magic_arguments, parse_argstring)
  import utils
  from hashlib import sha1
  
  
  def _codeToFilename(code):
      '''Convert code to a unique file name
  
      >>> _codeToFilename("int f(i){return i*i;}")
      'dbf7e731.C'
      '''
      fileNameBase = sha1(code).hexdigest()[0:8]
      return fileNameBase + ".C"
  
  def _dumpToUniqueFile(code):
      '''Dump code to file whose name is unique
  
      >>> _codeToFilename("int f(i){return i*i;}")
      'dbf7e731.C'
      '''
      fileName = _codeToFilename(code)
      ofile = open (fileName,'w')
      ofile.write(code)
      ofile.close()
      return fileName
  
  
  @magics_class
  class CppMagics(Magics):
  
      @cell_magic
      @magic_arguments()
      @argument('-a', '--aclic', action="store_true", help='Compile code with ACLiC.')
      @argument('-d', '--declare', action="store_true", help='Declare functions and/or classes.')
      def cpp(self, line, cell):
          args = parse_argstring(self.cpp, line)
          if args.aclic:
              fileName = _dumpToUniqueFile(cell)
              utils.invokeAclic(fileName) 
          elif args.declare:
              utils.declareCppCode(cell) 
          else:
              utils.processCppCode(cell)
  
  def load_ipython_extension(ipython):
      ipython.register_magics(CppMagics)
  
new_contents: 
  from IPython.core.magic import (Magics, magics_class, cell_magic)
  from IPython.core.magic_arguments import (argument, magic_arguments, parse_argstring)
  import utils
  from hashlib import sha1
  
  
  def _codeToFilename(code):
      '''Convert code to a unique file name
  
      >>> _codeToFilename("int f(i){return i*i;}")
      'dbf7e731.C'
      '''
      fileNameBase = sha1(code).hexdigest()[0:8]
      return fileNameBase + ".C"
  
  def _dumpToUniqueFile(code):
      '''Dump code to file whose name is unique
  
      >>> _codeToFilename("int f(i){return i*i;}")
      'dbf7e731.C'
      '''
      fileName = _codeToFilename(code)
      ofile = open (fileName,'w')
      ofile.write(code)
      ofile.close()
      return fileName
  
  
  @magics_class
  class CppMagics(Magics):
  
      @cell_magic
      @magic_arguments()
      @argument('-a', '--aclic', action="store_true", help='Compile code with ACLiC.')
      @argument('-d', '--declare', action="store_true", help='Declare functions and/or classes.')
      def cpp(self, line, cell):
          """Run a C++ cell in a Python notebook.
          """
          args = parse_argstring(self.cpp, line)
          if args.aclic:
              fileName = _dumpToUniqueFile(cell)
              utils.invokeAclic(fileName) 
          elif args.declare:
              utils.declareCppCode(cell) 
          else:
              utils.processCppCode(cell)
  
  def load_ipython_extension(ipython):
      ipython.register_magics(CppMagics)
  
subject: Add a message to the %%cpp magic documentation