-int gp_init_2(void);
-int window2(double xmin, double ymin, double xmax, double ymax);
-int window_2(double xmin, double ymin, double xmax, double ymax);
-int viewprt2(double xmin, double ymin, double xmax, double ymax);
-int viewport_2(double xmin, double ymin, double xmax, double ymax);
-int framevpt(void);
-int calc_wc_to_ndc(void);
-int calc_ndc_to_mc(void);
-int wc_to_ndc(double xw, double yw, double *xn, double *yn);
-int ndc_to_wc(double xn, double yn, double *xw, double *yw);
-int color(int icol);
-int linestyle(int style);
-int line_abs_2(double x, double y);
-int lineabs2(double x, double y);
-int move_abs_2(double x, double y);
-int moveabs2(double x, double y);
-int line_rel_2(double x, double y);
-int linerel2(double x, double y);
-int move_rel_2(double x, double y);
-int moverel2(double x, double y);
-int draw_text(char *message);
-int drawtext(char *message);
-int polylnabs2(double x[], double y[], int n);
-int markabs2(double x, double y);
-int markrel2(double x, double y);
-int pntabs2(double x, double y);
-int pntrel2(double x, double y);
-int ctm_clr_2(void);
-int ctm_get_2(GRFMTX_2D m);
-int ctm_set_2(GRFMTX_2D m);
-int ctm_pre_mult_2(GRFMTX_2D m);
-int ctm_post_mult_2(GRFMTX_2D m);
+void gp_init_2(void);
+void window2(double xmin, double ymin, double xmax, double ymax);
+void window_2(double xmin, double ymin, double xmax, double ymax);
+void viewprt2(double xmin, double ymin, double xmax, double ymax);
+void viewport_2(double xmin, double ymin, double xmax, double ymax);
+void framevpt(void);
+void calc_wc_to_ndc(void);
+void calc_ndc_to_mc(void);
+void wc_to_ndc(double xw, double yw, double *xn, double *yn);
+void ndc_to_wc(double xn, double yn, double *xw, double *yw);
+void color(int icol);
+void linestyle(int style);
+void line_abs_2(double x, double y);
+void lineabs2(double x, double y);
+void move_abs_2(double x, double y);
+void moveabs2(double x, double y);
+void line_rel_2(double x, double y);
+void linerel2(double x, double y);
+void move_rel_2(double x, double y);
+void moverel2(double x, double y);
+void draw_text(char *message);
+void drawtext(char *message);
+void polylnabs2(double x[], double y[], int n);
+void markabs2(double x, double y);
+void markrel2(double x, double y);
+void pntabs2(double x, double y);
+void pntrel2(double x, double y);
+void ctm_clr_2(void);
+void ctm_get_2(GRFMTX_2D m);
+void ctm_set_2(GRFMTX_2D m);
+void ctm_pre_mult_2(GRFMTX_2D m);
+void ctm_post_mult_2(GRFMTX_2D m);