This function converts the excel files into required R format.
ExcelToR(file_align = 'alignment.xlsx', null.tokens = TRUE, len = len)
the excel file name which we want to convert it into required R format.
logical. If TRUE, 'null' is added at the first of each source sentence of the test set.
the number of sheets of the excel file to be converted into R format. It must be assigned by the user.
an RData object as 'file_align.RData'.