Converts a unix timestamp to a human readable date/time

    :param float unix_timestamp: A unix timestamp

    :return: A date/time in the format YYYY-mm-dd HH:MM:SS
    :rtype: str

def _convert_to_datetime(unix_timestamp):
    '''
    Converts a unix timestamp to a human readable date/time

    :param float unix_timestamp: A unix timestamp

    :return: A date/time in the format YYYY-mm-dd HH:MM:SS
    :rtype: str
    '''
    try:
        unix_timestamp = float(unix_timestamp)
        return datetime.fromtimestamp(unix_timestamp).strftime('%Y-%m-%d %H:%M:%S')
    except (ValueError, TypeError):
        return 'Invalid Timestamp'