code: function () {
              var a = this.val;
  
              return (
                  a[0] === 1 &&
                  a[1] === 0 &&
                  a[2] === 0 &&
                  a[3] === 0 &&
                  a[4] === 1 &&
                  a[5] === 0 &&
                  a[6] === 0 &&
                  a[7] === 0 &&
                  a[8] === 1
              );
          }
docs: returns true if the matrix is an identity matrix.
  @name isIdentity
  @memberOf me.Matrix2d
  @function
  @return {Boolean}