message: Define only once
diff: @@ -20,7 +20,7 @@ namespace circle
  //
  template <typename F>
  -void for_each_line(F func, float radius = 1.0f, vec2 center = { 0.0f, 0.0f } )
  +static void for_each_line(F func, float radius = 1.0f, vec2 center = { 0.0f, 0.0f } )
  {
  for (int i = 0; i < 360; ++i)
  {
  @@ -42,7 +42,7 @@ void for_each_line(F func, float radius = 1.0f, vec2 center = { 0.0f, 0.0f } )
  //
  template <typename F>
  -void for_each_line(F func, vec3 vx, vec3 vy, vec3 center = { 0.0f, 0.0f, 0.0f } )
  +static void for_each_line(F func, vec3 vx, vec3 vy, vec3 center = { 0.0f, 0.0f, 0.0f } )
  {
  for (int i = 0; i < 360; ++i)
  {
  