>>> u = User.query.get(1)
>>> p = Post(body="my first post!", author=u)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 4, in __init__
  File "/mnt/c/Projects/flasklearn/microblog/venv/lib/python3.5/site-packages/sqlalchemy/orm/state.py", line 417, in _initialize_instance
    manager.dispatch.init_failure(self, args, kwargs)
  File "/mnt/c/Projects/flasklearn/microblog/venv/lib/python3.5/site-packages/sqlalchemy/util/langhelpers.py", line 66, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "/mnt/c/Projects/flasklearn/microblog/venv/lib/python3.5/site-packages/sqlalchemy/util/compat.py", line 187, in reraise
    raise value
  File "/mnt/c/Projects/flasklearn/microblog/venv/lib/python3.5/site-packages/sqlalchemy/orm/state.py", line 414, in _initialize_instance
    return manager.original_init(*mixed[1:], **kwargs)
  File "/mnt/c/Projects/flasklearn/microblog/venv/lib/python3.5/site-packages/sqlalchemy/ext/declarative/base.py", line 699, in _declarative_constructor
    (k, cls_.__name__))
TypeError: 'author' is an invalid keyword argument for Post
>>>