I'm new to Python and I'm facing some issues when it comes to private functions. I want to call two of them inside a public method, just for the sake of making the code look clear, but I cannot understand at all what the run-time error shows. Here is the problematic part of the complete code:

```
def __loadVec(self,vec,res):
    for i in range(0,res.getRows()):
        for j in range(0,res.getColumns()):
            vec.append(self.matrix[i][j])
    return

def __savetoMatrix(self,vec,res):
    index = 0
    for i in range(0,res.getRows()):
        for j in range(0,res.getColumns()):
            self.matrix[i][j] = vec[index]
            index += 1
    return

def fmatrixSort(self,res):
    try:
        print "Sorting matrix information..."
        vec = []
        self._matrix.__loadVec(vec,res)
        vec.sort()
        self_matrix.__savetoMatrix(vec,res)
    except TypeError:
        print "TypeError in fmatrixSort"            
    return

```

What I'm trying to do is to completely organize a matrix so as it starts with the lowest value and ends with the highest.

This is the error the program shows:

```
Traceback (most recent call last):
  File "MatrixClass.py", line 211, in <module>
    main()
  File "MatrixClass.py", line 203, in main
    mat.fmatrixSort(res)
  File "MatrixClass.py", line 154, in fmatrixSort
    self._matrix.__loadVec(vec,res)
AttributeError: matrix instance has no attribute '_matrix'

```

How should I fix this?