code: def get_docstring(self, project_path, source, position, filename):
          
          return self._call('get_docstring', project_path, source, position, filename)
docs: 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)