code: def create_calculator(code)
          code.split(/,(?=\d+:)/).each do |operation|
            col, term = operation.split(':', 2)
            term = "c#{col}#{term}" if term =~ /^[+\-*\/%]/
            formulae[col] = term
          end
        end
docs: given a csv file with a;b;c
   code is in the form of
   1:*2,2:*c3-1,4:c1+1
   1:*2 means multiply value from column 1 by 2 and assign it to column 1 c[1] = c[1]*2
   2:*c3-1 means multiply value from column 2 with value from column 3, subtract 1 and assign
   the result to column 2 c[2] = c[2] * c[3] - 1
   4:c1+1 means create a new column and assign to it the result of the sum of the value of
   column 1 + 1 c[4] = c[1] + 1