Validate a row label column.

    Parameters
    ----------
    label : str
        Name of the row label column.

    column_type_map : dict[str, type]
        Dictionary mapping the name of each column in an SFrame to the type of
        the values in the column.

def _validate_row_label(label, column_type_map):
    """
    Validate a row label column.

    Parameters
    ----------
    label : str
        Name of the row label column.

    column_type_map : dict[str, type]
        Dictionary mapping the name of each column in an SFrame to the type of
        the values in the column.
    """
    if not isinstance(label, str):
        raise TypeError("The row label column name must be a string.")

    if not label in column_type_map.keys():
        raise ToolkitError("Row label column not found in the dataset.")

    if not column_type_map[label] in (str, int):
        raise TypeError("Row labels must be integers or strings.")