def scrap_comments(sub, limit=10):
    """
        Function to scrap the top-10 comments(as it was done in data collection for training data)
        Params
            sub: submission instance
        Returns: top-10(if num_comments > 10 or top x) comments combined into single string with space
    """
    # agg into a list
    comments_body = []

    if sub.num_comments > 0:
        for i, comment in enumerate(sub.comments.list()):
            # There may be some comments which has no body
            try : 
                comments_body.append(comment.body)
            except:
                comments_body.append('')
            if i==limit:
                break

    return " ".join(comments_body)