S3 methods for tracking which additional packages are needed for steps.
# S3 method for step_depth
required_pkgs(x, ...)# S3 method for step_ica
required_pkgs(x, ...)
# S3 method for step_isomap
required_pkgs(x, ...)
# S3 method for step_kpca
required_pkgs(x, ...)
# S3 method for step_kpca_poly
required_pkgs(x, ...)
# S3 method for step_kpca_rbf
required_pkgs(x, ...)
# S3 method for step_nnmf
required_pkgs(x, ...)
# S3 method for step_pls
required_pkgs(x, ...)
# S3 method for step_window
required_pkgs(x, ...)
A recipe step
A character vector