docs: def get(self, requirement):
          """Find packages matching ``requirement``.
  
          :param requirement: Requirement to get from all underlying \
          repositories.
          :type requirement: `str` or :class:`.Requirement`
          :returns: :func:`list` of matching :class:`.Package` objects.
  
          """
          if isinstance(requirement, basestring):
              requirement = Requirement.parse(requirement)
          packages = set()
          for repository in self.repositories:
              packages |= set(repository.get(requirement))
          return sorted(packages)