to_s:
size: 21
to_json:
first: antenna_gain{"value":34343.0,"unit":"decibels_isotropic"}
product.metafields.custom["size"] =>
product.metafields.custom.size => 21

product.metafields.custom["first"] =>
product.metafields.custom.first => antenna_gain{"value":34343.0,"unit":"decibels_isotropic"}

product.metafields.custom["last"] =>
product.metafields.custom.last =>

product.metafields.custom["to_h"] =>
product.metafields.custom.to_h =>

product.metafields.custom["to_liquid"] =>
product.metafields.custom.to_liquid =>