code: def __step1(self):
          
          C = self.C
          n = self.n
          for i in range(n):
              minval = min(self.C[i])
              # Find the minimum value for this row and subtract that minimum
              # from every element in the row.
              for j in range(n):
                  self.C[i][j] -= minval
  
          return 2
docs: For each row of the matrix, find the smallest element and
          subtract it from every element in its row. Go to Step 2.