'append value to a list'

def append(self, path, value):

    try:
        entry = Yedit.get_entry(self.yaml_dict, path, self.separator)
    except KeyError:
        entry = None
    if (entry is None):
        self.put(path, [])
        entry = Yedit.get_entry(self.yaml_dict, path, self.separator)
    if (not isinstance(entry, list)):
        return (False, self.yaml_dict)
    entry.append(value)
    return (True, self.yaml_dict)
