capybara/virtualenv/lib/python2.7/site-packages/setuptools/__init__.py
def require_parents(packages):
        """
        Exclude any apparent package that apparently doesn't include its
        parent.

        For example, exclude 'foo.bar' if 'foo' is not present.
        """
        found = []
        for pkg in packages:
            base, sep, child = pkg.rpartition('.')
            if base and base not in found:
                continue
            found.append(pkg)
            yield pkg
def require_parents(packages):
        """
        Exclude any apparent package that apparently doesn't include its
        parent.

        For example, exclude 'foo.bar' if 'foo' is not present.
        """
        found = []
        for pkg in packages:
            base, sep, child = pkg.rpartition('.')
            if base and base not in found:
                continue
            found.append(pkg)
            yield pkg
Exclude any apparent package that apparently doesn't include its
        parent.

        For example, exclude 'foo.bar' if 'foo' is not present.