Extract multiple pmplots options
# S3 method for pm_opts
[(x, i, ..., exact = TRUE)the pm_opts object
a character option name to extract
other option names to extract
not used
pm["scatter.size", "time.unit"]
#> $scatter.size
#> [1] 1.5
#>
#> $time.unit
#> [1] "hr"
#>