code: function rotate(angle, cx, cy) {
      var cosAngle = cos(angle);
      var sinAngle = sin(angle);
      var rotationMatrix = {
          a: cosAngle, c: -sinAngle, e: 0,
          b: sinAngle, d: cosAngle, f: 0
      };
      if ((0, _utils.isUndefined)(cx) || (0, _utils.isUndefined)(cy)) {
          return rotationMatrix;
      }
  
      return (0, _transform.transform)([(0, _translate.translate)(cx, cy), rotationMatrix, (0, _translate.translate)(-cx, -cy)]);
  }
docs: Calculate a rotation matrix
  @param angle Angle in radians
  @param [cx] If (cx,cy) are supplied the rotate is about this point
  @param [cy] If (cx,cy) are supplied the rotate is about this point
  @returns {{a: number, b: number, c: number, e: number, d: number, f: number}} Affine matrix *