Given a list of [{'hash': ..., 'order': ...}], serialize it to a string.

def path_serialize(cls, path):
        """
        Given a list of [{'hash': ..., 'order': ...}], serialize it to a string.
        """
        # make it into a netstring
        path_parts = ['{}-{}'.format(p['order'], p['hash']) for p in path]
        path_ns_parts = ['{}:{},'.format(len(pp), pp) for pp in path_parts]
        path_str = ''.join(path_ns_parts)
        return '{}:{},'.format(len(path_str), path_str)