This function replaces all substituents in a glycan structure with empty strings.
Examples
(glycan <- o_glycan_core_1())
#> <glycan_structure[1]>
#> [1] Gal(b1-3)GalNAc(a1-
#> # Unique structures: 1
remove_substituents(glycan)
#> <glycan_structure[1]>
#> [1] Gal(b1-3)GalNAc(a1-
#> # Unique structures: 1
