docs: def group(merge_func, tokens):
  	"""
  	Group together those of the tokens for which the merge function returns
  	true. The merge function should accept two arguments/tokens and should
  	return a boolean indicating whether the strings should be merged or not.
  
  	Helper for tokenise(string, ..).
  	"""
  	output = []
  
  	if tokens:
  		output.append(tokens[0])
  
  		for token in tokens[1:]:
  			prev_token = output[-1]
  
  			if merge_func(prev_token, token):
  				output[-1] += token
  			else:
  				output.append(token)
  
  	return output