public int Write(ObservationWriter writer)
        {
            if (m_Board.Rows != m_Rows || m_Board.Columns != m_Columns || m_Board.NumCellTypes != m_NumCellTypes)
            {
                Debug.LogWarning(
                    $"Board shape changes since sensor initialization. This may cause unexpected results. " +
                    $"Old shape: Rows={m_Rows} Columns={m_Columns}, NumCellTypes={m_NumCellTypes} " +
                    $"Current shape: Rows={m_Board.Rows} Columns={m_Board.Columns}, NumCellTypes={m_Board.NumCellTypes}"
                );
            }


            if (m_ObservationType == Match3ObservationType.Vector)
            {
                int offset = 0;
                for (var r = 0; r < m_Rows; r++)
                {
                    for (var c = 0; c < m_Columns; c++)
                    {
                        var val = m_Board.GetCellType(r, c);
                        for (var i = 0; i < m_NumCellTypes; i++)
                        {
                            writer[offset] = (i == val) ? 1.0f : 0.0f;
                            offset++;
                        }

                        if (m_NumSpecialTypes > 0)
                        {
                            var special = m_Board.GetSpecialType(r, c);
                            for (var i = 0; i < SpecialTypeSize; i++)
                            {
                                writer[offset] = (i == special) ? 1.0f : 0.0f;
                                offset++;
                            }
                        }
                    }
                }

                return offset;
            }
            else
            {
                // TODO combine loops? Only difference is inner-most statement.


                float[,] m_Valid =new float[m_Board.Rows, m_Board.Columns];
                for (int i = 0; i < m_Board.Rows; i++)
                {
                    for (int j = 0; j < m_Board.Columns; j++)
                    {
                        m_Valid[i, i] = 0.0f;
                    }
                }

                foreach (var move in m_Board.ValidMoves())
                {
                    m_Valid[move.Row, move.Column] = 1.0f;
                }

                int offset = 0;

                for (var r = 0; r < m_Rows; r++)
                {
                    for (var c = 0; c < m_Columns; c++)
                    {
                        writer[r, c, 0] = m_Valid[r, c];
                        offset++;
                        var val = m_Board.GetCellType(r, c);
                        for (var i = 1; i < m_NumCellTypes+1; i++)
                        {
                            writer[r, c, i] = (i == val) ? 1.0f : 0.0f;
                            offset++;
                        }


                        if (m_NumSpecialTypes > 0)
                        {
                            var special = m_Board.GetSpecialType(r, c);
                            for (var i = 0; i < SpecialTypeSize; i++)
                            {
                                writer[offset] = (i == special) ? 1.0f : 0.0f;

                                offset++;
                            }
                        }

                    }
                }

                return offset;
            }
        }