remove unused Statement.get_command function

jedi/parsing_representation.py

@@ -836,13 +836,6 @@ class Statement(Simple):
         # first keyword of the first token is global -> must be a global
         return str(self.token_list[0]) == "global"
 
-    def get_command(self, index):
-        commands = self.get_commands()
-        try:
-            return commands[index]
-        except IndexError:
-            return None
-
     @property
     def assignment_details(self):
         # parse statement which creates the assignment details.