[commands] implement HelpCommand.add/remove_check

discord/ext/commands/help.py

@@ -326,6 +326,49 @@ class HelpCommand:
         self._command_impl._eject_cog()
         self._command_impl = None
 
+    def add_check(self, func):
+        """
+        Adds a check to the help command.
+
+        .. versionadded:: 1.4
+
+        Parameters
+        ----------
+        func
+            The function that will be used as a check.
+        """
+
+        if self._command_impl is not None:
+            self._command_impl.add_check(func)
+        else:
+            try:
+                self.command_attrs["checks"].append(func)
+            except KeyError:
+                self.command_attrs["checks"] = [func]
+
+    def remove_check(self, func):
+        """
+        Removes a check from the help command.
+
+        This function is idempotent and will not raise an exception if
+        the function is not in the command's checks.
+
+        .. versionadded:: 1.4
+
+        Parameters
+        ----------
+        func
+            The function to remove from the checks.
+        """
+
+        if self._command_impl is not None:
+            self._command_impl.remove_check(func)
+        else:
+            try:
+                self.command_attrs["checks"].remove(func)
+            except (KeyError, ValueError):
+                pass
+
     def get_bot_mapping(self):
         """Retrieves the bot mapping passed to :meth:`send_bot_help`."""
         bot = self.context.bot