Facundo Batista recommends something along these lines for the part processing def splitgen(text, sep): pos_from = 0 while True: try: pos_to = text.index(sep, pos_from) except ValueError: yield text[pos_from:] break yield text[pos_from:pos_to] pos_from = pos_to + len(sep) test = [ 'foo', 'foo\n---\nbar', 'foo\n---\n', 'foo\n---\nbar\n---\n', 'foo\n---\n\n---\nbar\n---\n', ] for t in test: assert t.split("\n---\n") == list(splitgen(t, "\n---\n"))