Search across all (without field) or in specific field
        (valid fields at http://www.loc.gov/standards/mods/mods-outline.html)

def search(self, q, field=None, page=None, per_page=None):
        """Search across all (without field) or in specific field
        (valid fields at http://www.loc.gov/standards/mods/mods-outline.html)"""

        def picker(results):
            if type(results['result']) == list:
                return results['result']
            else:
                return [results['result']]

        return self._get(('search',), picker, q=q, field=field, page=page, per_page=per_page)