from typing import List


def columns_to_rows(columns: list) -> List[List[str]]:
    """ Split an arbitrary number of columns into enough
    rows to hold three columns worth of data. """
    output = []
    for i in range(0, 3):
        current = []
        for j in range(0, int(len(columns) / 3)):
            current.append(columns[i + j * 3])
        output.append(current)
    return output