Function modify_size 

pub fn modify_size(height: usize, width: usize) -> ControlSequence

GSM - Graphic size modification

GSM is used to modify for subsequent text the height and/or the width of all primary and alternative fonts identified by FONT SELECTION (FNT) and established by GRAPHIC SIZE SELECTION (GSS).

The established values remain in effect until the next occurrence of GSM or GSS in the data steam.

height and width are percentage of values established by GSS (select_size).