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.

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)