'Return a document string for this completion object.
Example:
>>> from jedi import Script
>>> source = \'\'\'\
... def f(a, b=1):
...     "Document for function f."
>>> script = Script(source, 1, len(\'def f\'), \'example.py\')
>>> doc = script.goto_definitions()[0].docstring()
>>> print(doc)
f(a, b=1)
<BLANKLINE>
Document for function f.
Notice that useful extra information is added to the actual
docstring.  For function, it is call signature.  If you need
actual docstring, use ``raw=True`` instead.
>>> print(script.goto_definitions()[0].docstring(raw=True))
Document for function f.
:param fast: Don\'t follow imports that are only one level deep like
``import foo``, but follow ``from foo import bar``. This makes
sense for speed reasons. Completing `import a` is slow if you use
the ``foo.docstring(fast=False)`` on every object, because it
parses all libraries starting with ``a``.'

def docstring(self, raw=False, fast=True):

    return _Help(self._name).docstring(fast=fast, raw=raw)
