Added comments.

ipymd/formats/markdown.py

@@ -164,6 +164,8 @@ class MarkdownReader(BaseMarkdownReader):
 
     def _has_input_prompt(self, lines):
         """Return whether the line or set of lines has an input prompt."""
+        # Note: the rstrip() is necessary for empty lines with the
+        # leading '...' prompt but not the trailing space. See PR #25.
         if isinstance(lines, list):
             return any(line for line in lines
                        if line.startswith(self.prompt_first.rstrip()))

ipymd/formats/tests/test_markdown.py

@@ -54,7 +54,7 @@ def test_markdown_markdown():
 
 
 def test_decorator():
-
+    """Test a bug fix where empty '...' lines were added to the output."""
     markdown = '\n'.join(('```python',
                           '>>> @decorator',
                           '... def f():',