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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_docstring(self, project_path, source, position, filename):
 """Return signature and docstring for current cursor call context Some examples of call context:: func(| func(arg| func(arg,| func(arg, func2(| # call context is func2 Signature and docstring can be None :param project_path: absolute project path :param source: unicode or byte string code source :param position: character or byte cursor position :param filename: absolute path of file with source code :returns: tuple (signarure, docstring) """

        return self._call('get_docstring', project_path, source, position, filename)