def gravity(grav)
      Kernel.raise ArgumentError, 'Unknown text positioning gravity' unless GRAVITY_NAMES.key?(grav.to_i)
      primitive "gravity #{GRAVITY_NAMES[grav.to_i]}"
    end
def gravity(grav)
      Kernel.raise ArgumentError, 'Unknown text positioning gravity' unless GRAVITY_NAMES.key?(grav.to_i)
      primitive "gravity #{GRAVITY_NAMES[grav.to_i]}"
    end
Specify the text positioning gravity, one of:
 NorthWest, North, NorthEast, West, Center, East, SouthWest, South, SouthEast