<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def json_to_string(value, null_string_repr='[]', trimable=False):
 """ Return a string representation of the specified JSON object. @param value: a JSON object. @param null_string_rep: the string representation of the null object. @return: a string representation of the specified JSON object. """

    return null_string_repr if is_undefined(value) \
        else obj.jsonify(value, trimable=trimable)