def _adjmatType(adjMat):
    """(helper function) retruns <class 'int'> if the adjacency matrix is a (0,1)-matrix, and
    returns <class 'list'> if the adjacency matrix contains edge weights, and returns None if
    neither of the cases occurs.

    Args:
        adjMat (2D - nested - list): the adjacency matrix.
    Returns:
        (type) the type of the adjacency matrix as explained above.
    """
    checktype = {all(isinstance(entry, list) for entry in row) for row in adjMat}
    if len(checktype) == 1 and checktype.pop() == True: return list

    checktype = {all(isinstance(entry, int) for entry in row) for row in adjMat}
    if len(checktype) == 1 and checktype.pop() == True: return int

    return None