TERT and central nervous system cancer: An extensive analysis of various feature selection methods and ML algorithms resulted in the SVM model that classifies gliomas as astrocytoma, oligodendroglioma, or glioblastoma using the expression of 13 genes (TERT, NOX4, MMP9, TRIM67, ZDHHC18, HDAC1, TUBB6, ADM, NOG, CHEK2, KCNJ11, KCNIP2, and VEGFA).