'Initialise an instance.
:param metadata: The instance of :class:`Metadata` describing this
distribution.'

def __init__(self, metadata):

    self.metadata = metadata
    self.name = metadata.name
    self.key = self.name.lower()
    self.version = metadata.version
    self.locator = None
    self.digest = None
    self.extras = None
    self.context = None
