Traceback (most recent call last):


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/bin/pipenv", line 11, in <module>

load_entry_point('pipenv==2018.11.26', 'console_scripts', 'pipenv')()


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/vendor/click/core.py", line 764, in __call__

return self.main(*args, **kwargs)


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/vendor/click/core.py", line 717, in main

rv = self.invoke(ctx)


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/vendor/click/core.py", line 1137, in invoke

return _process_result(sub_ctx.command.invoke(sub_ctx))


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/vendor/click/core.py", line 956, in invoke

return ctx.invoke(self.callback, **ctx.params)


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/vendor/click/core.py", line 555, in invoke

return callback(*args, **kwargs)


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/vendor/click/decorators.py", line 64, in new_func

return ctx.invoke(f, obj, *args, **kwargs)


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/vendor/click/core.py", line 555, in invoke

return callback(*args, **kwargs)


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/vendor/click/decorators.py", line 17, in new_func

return f(get_current_context(), *args, **kwargs)


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/cli/command.py", line 254, in install

editable_packages=state.installstate.editables,


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/core.py", line 1741, in do_install

pypi_mirror=pypi_mirror,


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/core.py", line 609, in ensure_project

validate=validate, skip_requirements=skip_requirements, system=system


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/core.py", line 320, in ensure_pipfile

project.create_pipfile(python=python)


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/project.py", line 726, in create_pipfile

required_python = self.which("python", self.virtualenv_location)


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/project.py", line 1083, in which

result = next(iter(filter(None, (find(finder) for finder in self.finders))), None)


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/project.py", line 1083, in <genexpr>

result = next(iter(filter(None, (find(finder) for finder in self.finders))), None)


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/vendor/pythonfinder/pythonfinder.py", line 67, in which

return self.system_path.which(exe)


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/vendor/pythonfinder/pythonfinder.py", line 54, in system_path

ignore_unsupported=self.ignore_unsupported,


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/vendor/pythonfinder/models/path.py", line 451, in create

ignore_unsupported=ignore_unsupported,


 "<attrs generated init 75e45f144e3d5510d54dd5fca6730b98fa0220a9>", line 38, in __init__


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/vendor/pythonfinder/models/path.py", line 116, in __attrs_post_init__

self._setup_pyenv()


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/vendor/pythonfinder/models/path.py", line 196, in _setup_pyenv

version_glob_path="versions/*", ignore_unsupported=self.ignore_unsupported


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/vendor/pythonfinder/models/python.py", line 156, in create

sort_function=sort_function, version_glob_path=version_glob_path)


 "<attrs generated init e10e89ae41c3b673beaf8c9439cf2f48dc63d342>", line 21, in __init__


 "/usr/local/Cellar/pipenv/2018.11.26/libexec/lib/python3.7/site-packages/pipenv/vendor/pythonfinder/models/python.py", line 147, in get_pythons

pythons.update(p.pythons)
AttributeError: 'NoneType' object has no attribute 'pythons'

Traceback (most recent call last):


 "check.py", line 13, in <module>

l.backward()


 "/hoge/lib/python3.6/site-packages/chainer/variable.py", line 852, in backward

self._backward_main(retain_grad)


 "/hoge/lib/python3.6/site-packages/chainer/variable.py", line 953, in _backward_main

target_input_indexes, out_grad, in_grad)


 "/hoge/lib/python3.6/site-packages/chainer/function_node.py", line 509, in backward_accumulate

gxs = self.backward(target_input_indexes, grad_outputs)


 "/hoge/lib/python3.6/site-packages/chainer/function.py", line 139, in backward

gxs = self._function.backward(in_data, grad_out_data)


 "/hoge/lib/python3.6/site-packages/chainer/functions/activation/lstm.py", line 186, in backward

ggc = ggc_prev.copy()
AttributeError: 'NoneType' object has no attribute 'copy'
