v::VegaVisualization

color::String = "Black"
width::Real = 0.75
opacity::Real = 1
visible::Bool = true

using Vega, DataFrames
category = ['A', 'A', 'A', 'A', 'B', 'B', 'B', 'B', 'C', 'C', 'C', 'C']
position = [0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3]
value = [0.1, 0.6, 0.9, 0.4, 0.7, 0.2, 1.1, 0.8, 0.6, 0.2, 0.1, 0.7]

a = groupedbar(x = category, y = value, position = position)

stroke!(v, width = 1.5)