from datetime import datetime


def make_timestamp_instance(timestamp_string: str) -> datetime:
    """Converts a string timestamp to a timestamp object
    Arguments:
        timestamp_string: the timestamp to convert (see Notes)
    Return:
        Returns a timestamp object representing the timestamp passed in
    Notes:
        Only accepts timestamp strings with the following format:
            "MM/DD/YYYY HH:MI:SS"
            "YYYY.MM.DD-HH:MI:SS"
    """
    if '.' in timestamp_string:
        return datetime.strptime(timestamp_string, '%Y.%m.%d-%H:%M:%S')

    return datetime.strptime(timestamp_string, '%m/%d/%Y %H:%M:%S')