isnative

You can use isnative to test for command implementation in the host environment.

For example:

declare circle 'company.product.shape.circle'

if isnative circle
  # safe to use circle
  var c = circle 0, 0, 50
  #...
else
  # can't use circle, maybe use something else
end

This might be useful for detecting if certain features are available without aborting the script.