code: public StringExpression geometryType() {
          if (geometryType == null) {
              geometryType = Expressions.stringOperation(SpatialOps.GEOMETRY_TYPE, mixin);
          }
          return geometryType;
      }
docs: Returns the name of the instantiable subtype of Geometry of which this
  geometric object is an instantiable member. The name of the subtype of Geometry is returned as a string.
  
  @return geometry type