expected: load sheets by name, they should correspond to the named sheets in the file
observed: unfortunately, the sheet names are unreliable, The order in which they are listed is the same as the actual workbook, but the names are mixed up. IE: the first sheet in the book is still the first sheet in the array, but it's name may or not be the same, so that using get_sheet_by_name, may not work.
It seems that if the workbook has charts as sheets, then there names will get loaded.
'work' has sheet1: 'hello' sheet2: 'graph1' (a chart) sheet3: 'bye'
>>> wb = load_workbook('work') >>> wb.get_sheet_names() ['hello', 'graph1', 'bye']
see the problem!