How to use the parsel.__version__ function in parsel

try:
        w3lib_version = w3lib.__version__
    except AttributeError:
        w3lib_version = "<1.14.3"
    try:
        import cryptography
        cryptography_version = cryptography.__version__
    except ImportError:
        cryptography_version = "unknown"

    return [
        ("Scrapy", scrapy.__version__),
        ("lxml", lxml_version),
        ("libxml2", libxml2_version),
        ("cssselect", cssselect.__version__),
        ("parsel", parsel.__version__),
        ("w3lib", w3lib_version),
        ("Twisted", twisted.version.short()),
        ("Python", sys.version.replace("\n", "- ")),
        ("pyOpenSSL", _get_openssl_version()),
        ("cryptography", cryptography_version),
        ("Platform",  platform.platform()),
    ]

# The encoding of source files.
#source_encoding = 'utf-8-sig'

# The master toctree document.
master_doc = 'index'

# General information about the project.
project = u'Parsel'
copyright = u'2015, Scrapy Project'

# The version info for the project you're documenting, acts as replacement
# for |version| and |release|, also used in various other places throughout
# the built documents.
#
# The short X.Y version.
version = parsel.__version__
# The full version, including alpha/beta/rc tags.
release = parsel.__version__

# The language for content autogenerated by Sphinx. Refer to documentation
# for a list of supported languages.
#language = None

# There are two options for replacing |today|: either, you set today to
# some non-false value, then it is used:
#today = ''
# Else, today_fmt is used as the format for a strftime call.
#today_fmt = '%B %d, %Y'

# List of patterns, relative to source directory, that match files and
# directories to ignore when looking for source files.
exclude_patterns = ['_build']

# The master toctree document.
master_doc = 'index'

# General information about the project.
project = u'Parsel'
copyright = u'2015, Scrapy Project'

# The version info for the project you're documenting, acts as replacement
# for |version| and |release|, also used in various other places throughout
# the built documents.
#
# The short X.Y version.
version = parsel.__version__
# The full version, including alpha/beta/rc tags.
release = parsel.__version__

# The language for content autogenerated by Sphinx. Refer to documentation
# for a list of supported languages.
#language = None

# There are two options for replacing |today|: either, you set today to
# some non-false value, then it is used:
#today = ''
# Else, today_fmt is used as the format for a strftime call.
#today_fmt = '%B %d, %Y'

# List of patterns, relative to source directory, that match files and
# directories to ignore when looking for source files.
exclude_patterns = ['_build']

# The reST default role (used for this markup: `text`) to use for all