15. The server computer system of claim 11 , wherein pruning the preliminary plurality of text tokens comprises selecting a target text token of the preliminary plurality of text tokens into the selected plurality of text tokens according to a hash of the target text token.
16. The server computer system of claim 15 , wherein pruning the preliminary plurality of text tokens further comprises: determining whether the hash of the target text token is divisible by a zoom-out factor; and in response, when the target text token is divisible by the zoom-out factor, selecting the target text token into the selected plurality of text tokens.