How to changes ``scm`` variable

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I am loooking for a way to copy the scm variable to modify it in a custom checkout function
how can I do this, without modifying the global scm variable?

def scmCopy = scm.makeCopy() // somehow copy this??
scmCopy.getExtensions().remove([$class: 'GitLFSPull'])
checkout(scmCopy)