Add Markov.add function

This is basically just a shorthand, but also abstracts away adding a
line to a markov chain

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

plugins/markov.py

@@ -104,7 +104,10 @@ class Markov(Plugin):
             self.handle_command(conn, channel, who, parts)
         elif line[0] != "!":
             # ignore other commands
-            self.chains[channel][who.nick].add(line)
+            self.add(channel, who.nick, line)
+
+    def add(self, channel: str, who: str, line: str):
+        self.chains[channel][who].add(line)
 
     def handle_command(
         self, conn: IrcProtocol, channel: str, who: Prefix, parts: Sequence[str]