Add codesnippet for almost chronological order

Such as for downloading hashtag feeds, as discussed in #666 and contributed by
@e2tovar.

Also change comment color to grey in codesnippets in documentation.

docs/_static/instaloader.css

@@ -17,7 +17,9 @@ code {
   .highlight pre {
     padding: 0.7em;
     color: #fff; }
-  .highlight .c1, .highlight .k, .highlight .kn, .highlight .ow {
+  .highlight .c1 {
+    color: #666; }
+  .highlight .k, .highlight .kn, .highlight .ow {
     color: #008d06; }
   .highlight .nb, .highlight .ne, .highlight .nf, .highlight .vm {
     color: #f48400; }

docs/_static/instaloader.scss

@@ -36,7 +36,11 @@ code {
     color: #fff;
   }
 
-  .c1, .k, .kn, .ow {
+  .c1 {
+    color: #666;
+  }
+
+  .k, .kn, .ow {
     color: $color_instaloader_main
   }
 

docs/codesnippets.rst

@@ -28,8 +28,9 @@ Download Posts in a Specific Period
 -----------------------------------
 
 To only download Instagram pictures (and metadata) that are within a specific
-period, you can play around with :func:`~itertools.dropwhile` and
-:func:`~itertools.takewhile` from :mod:`itertools` like in this snippet.
+period, you can simply use :func:`~itertools.dropwhile` and
+:func:`~itertools.takewhile` from :mod:`itertools` on a generator that returns
+Posts in **exact chronological order**, such as :meth:`Profile.get_posts`.
 
 .. literalinclude:: codesnippets/121_since_until.py
 
@@ -37,6 +38,14 @@ See also :class:`Post`, :meth:`Instaloader.download_post`.
 
 Discussed in :issue:`121`.
 
+The code example with :func:`~itertools.dropwhile` and
+:func:`~itertools.takewhile` makes the assumption that the post iterator returns
+posts in exact chronological order.  As discussed in :issue:`666`, the following
+approach fits for an **almost chronological order**, where up to *k* older posts
+are inserted into an otherwise chronological order, such as an Hashtag feed.
+
+.. literalinclude:: codesnippets/666_historical_hashtag_data.py
+
 Likes of a Profile / Ghost Followers
 ------------------------------------
 

docs/codesnippets/121_since_until.py

@@ -5,13 +5,11 @@ import instaloader
 
 L = instaloader.Instaloader()
 
-posts = instaloader.Hashtag.from_name(L.context, 'urbanphotography').get_posts()
-# or
-# posts = instaloader.Profile.from_username(L.context, PROFILE).get_posts()
+posts = instaloader.Profile.from_username(L.context, "instagram").get_posts()
 
 SINCE = datetime(2015, 5, 1)
 UNTIL = datetime(2015, 3, 1)
 
 for post in takewhile(lambda p: p.date > UNTIL, dropwhile(lambda p: p.date > SINCE, posts)):
     print(post.date)
-    L.download_post(post, '#urbanphotography')
+    L.download_post(post, "instagram")

docs/codesnippets/666_historical_hashtag_data.py

@@ -0,0 +1,30 @@
+from datetime import datetime
+import instaloader
+
+L = instaloader.Instaloader()
+
+posts = instaloader.Hashtag.from_name(L.context, "urbanphotography").get_posts()
+
+SINCE = datetime(2020, 5, 10)  # further from today, inclusive
+UNTIL = datetime(2020, 5, 11)  # closer to today, not inclusive
+
+k = 0  # initiate k
+k_list = []  # uncomment this to tune k
+
+for post in posts:
+    postdate = post.date
+
+    if postdate > UNTIL:
+        continue
+    elif postdate <= SINCE:
+        k += 1
+        if k == 50:
+            break
+        else:
+            continue
+    else:
+        L.download_post(post, "#urbanphotography")
+        k = 0  # set k to 0
+        # if you want to tune k, uncomment below to get your k max
+        #k_list.append(k)
+#max(k_list)