function getIconSize(props) {
  const { spacing } = props.theme;
  const { icon } = props.style;

  if (icon && icon.width) {
    return icon.width;
  }
  if (props.size) {
    return props.size;
  }

  return spacing.iconSize;
}
Returns size of icon. Priority order: style prop, size prop, spacing.iconSize.