This function modifies the (linear) internal list and sets the desired parameters (based on the instruction string) to 0. This indicates that this parameter is not altered within the function x2prms_vals (i.e., ' prm <!> conda')
flex_fix_prms(flex_prms_obj, formula_instr)a modified flex_prms_obj with respect to the (linear) internal list
a flex_prms object
a string referring to "fix" (see modify_flex_prms)