Rev0 Holds scenario appears incorrect

[rserna2010]

Tho the specs / examples show this same syntax:
https://docs.balancedpayments.com/1.0/overview/processing/#holds

It returns: NoMethodError: undefined method `hold' for #<Balanced::Customer

This syntax works instead:
hold = Balanced::Hold.new(:source_uri => "/v1/customers/ACO702cHD2tPiOCRSKYzVf1/cards/CCQv8XnGsBHF9afrEdc0um3", :amount=>500)
hold.save