def _get_upload_name(self, filename):
        import hashlib
        import random

        while True:
            hasher = hashlib.md5()
            hasher.update(str(random.random()))
            filepath = u"identities/" + hasher.hexdigest() + u"__" + filename
            fullpath = settings.MEDIA_ROOT + filepath
            if not default_storage.exists(fullpath):
                return filepath
Inserts a list-of-lists as rows into spreadsheet from lastrowused.
dataset/ETHPy150Open treeio/treeio/treeio/identities/forms.py/ContactForm._get_upload_name--crossover with--dataset/ETHPy150Open miklevin/pipulate/common.py/InsertRows