sizes top-level constant
common ad image sizes.
Implementation
const List<String> sizes = [
'300x250',
'250x250',
'240x400',
'336x280',
'180x150',
'720x300',
'468x60',
'234x60',
'88x31',
'120x90',
'120x60',
'120x240',
'125x125',
'728x90',
'160x600',
'120x600',
'300x600'
];