from typing import List


def slices(series: str, length: int) -> List[str]:
    """

    :param series: str: A sequence of integers
    :param length: int: Length of sub-sequences to be returned
    :return: List[str]: A list of all sub-series of length 'length' of the given series
    """
    # Check if given length is non-zero and less than (or equal) the length of string
    if 0 < length <= len(series) and series:
        return [series[start:(start + length)] for start in range(0, len(series) - length + 1)]
    raise ValueError("Invalid inputs for slicing the series !!")