$default-variables: (
  "Button-Icon____radius": var(--radius--circle),
  "Button-Icon____transition-duration": var(--timing--hover)
);

@mixin generate-button-icon-theme-variables($theme-variables: ()) {
  $variables: map-merge($default-variables, $theme-variables);

  @each $name, $value in $variables {
    --#{$name}: #{$value};
  }
}