A fairly widespread practice is that for which the price is paid by taking over the remaining loan already present on the property to be purchased.
The assumption, in legally, is a transaction governed by Article 1273 of the Civil Code:
"If the debtor and a third party agree that such third party assumes the debt of the other, the creditor may accede to the Convention, making the irrevocable stipulation in his favor."
Therefore it is called
Liberating assumption: if there is adhesion of the bank
Internal assumption (cumulative): no adhesion of the bank