code: def get_shebang(tokens):
      
      # This (short) loop preserves shebangs and encoding strings:
      for tok in tokens[0:4]: # Will always be in the first four tokens
          line = tok[4]
          # Save the first comment line if it starts with a shebang
          # (e.g. '#!/usr/bin/env python')
          if shebang.match(line): # Must be first line
              return line
docs: Returns the shebang string in *tokens* if it exists.  None if not.