import re


def is_timestamp(string):
    """Tests if the input string is formatted as -yyyy-mm-dd hh:mm:ss"""
    reg_exp = re.compile(r'-\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}')
    if reg_exp.match(string) is not None:
        return True
    return False