R Under development (unstable) (2023-10-26 r85419 ucrt) -- "Unsuffered Consequences"
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> library(grid)
> library(grImport2)
> library(gridSVG)

Attaching package: 'gridSVG'

The following objects are masked from 'package:grid':

    linearGradient, pattern, radialGradient

The following object is masked from 'package:grDevices':

    dev.off

> 
> pic <- readPicture("test-defs-input.svg")
Warning message:
In checkValidSVG(doc, warn = warn) :
  This picture may not have been generated by Cairo graphics; errors may result
> 
> gridsvg("test-defs-output.svg", width = 6, height = 6, annotate=FALSE)
> grid.picture(pic, expansion = 0)
> dev.off()
> 
> proc.time()
   user  system elapsed 
   0.82    0.10    0.92