Canonicalization of DGPs is a stateful procedure, hence the need for a class.
# S4 method for class 'DgpCanonMethods'
names(x)
# S4 method for class 'DgpCanonMethods'
x$namenames(DgpCanonMethods): Returns the name of all the canonicalization methods
$: Returns either a canonicalized variable or
a corresponding Dgp2Dcp canonicalization method