Find a package using package finders.

        Return the first package found.

        Args:
            package (str): package to find.
            **kwargs (): additional keyword arguments used by finders.

        Returns:
            PackageSpec: if package found, else None

def find(self, package, **kwargs):
        """
        Find a package using package finders.

        Return the first package found.

        Args:
            package (str): package to find.
            **kwargs (): additional keyword arguments used by finders.

        Returns:
            PackageSpec: if package found, else None
        """
        for finder in self.finders:
            package_spec = finder.find(package, **kwargs)
            if package_spec:
                return package_spec
        return None