def coordinates=(c)
      case c
      when String
        @coordinates = c.split(/\s+/).collect { |coord| coord.split(',') }
      when Array
        c.each do |coord_array|
          unless coord_array.is_a?(Array)
            raise ArgumentError, "If set with an array, coordinates must be specified as an array of arrays"
          end
        end
        @coordinates = c
      else
        raise ArgumentError, "Coordinates must either be a String or an Array of Arrays"
      end
    end
def coordinates=(c)
      case c
      when String
        @coordinates = c.split(/\s+/).collect { |coord| coord.split(',') }
      when Array
        c.each do |coord_array|
          unless coord_array.is_a?(Array)
            raise ArgumentError, "If set with an array, coordinates must be specified as an array of arrays"
          end
        end
        @coordinates = c
      else
        raise ArgumentError, "Coordinates must either be a String or an Array of Arrays"
      end
    end
Set the coordinates