def build_column_map(colspecstr):
    #
    if not colspecstr:
        return collections.OrderedDict()
    if hasattr(colspecstr, 'items'):
        return colspecstr
    return collections.OrderedDict(
        parse_colspecstr(colspecstr, default=unicode)
    )
Given a (row, col) tuple, return the corresponding index.
dataset/ETHPy150Open westurner/pyline/pyline.py/build_column_map--crossover with--dataset/ETHPy150Open jonathanslenders/python-prompt-toolkit/prompt_toolkit/document.py/Document.translate_row_col_to_index