code: def set_value(self, column, row, value):
          
          self.matrix[column][row] = value
docs: Set the value of the Matrix at the specified column and row.
  
          :param integer column:  The index for the column (starting at 0)
          :param integer row:     The index for the row (starting at 0)
          :param numeric value:   The new value at the given column/row
  
          :raise:     Raises an :py:exc:`IndexError` if the index is out of xrange.