module Pagy::SharedExtra::Pagy

def sequels(steps = nil)

Notice: if :steps is false it will use the single {0 => @vars[:size]} size
"550" => [1, 2, 3, :gap, 16, 17, 18, 19, "20", 21, 22, 23, 24, :gap, 48, 49, 50] }
"350" => [1, 2, :gap, 17, 18, 19, "20", 21, 22, 23, :gap, 49, 50],
#=> { "0" => [1, :gap, 18, 19, "20", 21, 22, :gap, 50],
>> pagy.sequels
>> pagy = Pagy.new(count:1000, page: 20, steps: {0 => [1,2,2,1], 350 => [2,3,3,2], 550 => [3,4,4,3]})
Example:
It returns the sequels of width/series generated from the :steps hash
`Pagy` instance method used by the `pagy*_nav_js` helpers.
def sequels(steps = nil)
  steps ||= @vars[:steps] || { 0 => @vars[:size] }
  raise VariableError.new(self, :steps, 'to define the 0 width', steps) unless steps.key?(0)
  {}.tap do |sequels|
    steps.each { |width, size| sequels[width.to_s] = series(size) }
  end
end