Creates a new Excel spreadsheet object. Parameter packed: :zip - File is a zip-file

returns the content of a cell. The upper left corner is (1,1) or (‘A’,1)

returns the type of a cell: :float, :string, :date, :time

returns all values in this column as an array column numbers are 1,2,3,… like in the spreadsheet

returns the first non empty column

returns the first non empty row

returns NO formula in excel spreadsheets

raises an exception because formulas are not supported for excel files

returns NO formulas in excel spreadsheets

TODO: testing only

returns the last non empty column

returns the last non empty row

returns all values in this row as an array row numbers are 1,2,3,… like in the spreadsheet

returns an array of sheet names in the spreadsheet