def get_coordinates(sub_turn):
    """
    Obtain coordinates entered by human user

    Attributes
    ----------
    sub_turn: str
        Game's sub turn. Used to prompt user.
    """
    print(sub_turn, 'phase')
    user_input = input("Please input in following format: xy ")
    column, row = -1, -1  # Adding this in in case other issues aren't caught
    if len(user_input) != 2:
        print("Please enter two digits")
        return -1, -1
    try:
        column = int(user_input[0])
        row = int(user_input[1])

        if column > 4 or row > 4:
            print("Please enter numbers between 0 and 4 (inclusive)")
            column, row = -1, -1

    except TypeError:
        print("Invalid entry. Example of valid entry: 03")
        column, row = -1, -1
    except ValueError as v:
        column, row = -1, -1
        print(v)
    finally:
        return column, row