class ActionView::LookupContext

def formats=(values)

Experimental RBS support (using type sampling data from the type_fusion project). 

def formats=: (Array[Symbol] value) -> Array[Symbol]

This signature was generated using 1 sample from 1 application.

add :html as fallback to :js.
Override formats= to expand ["*/*"] values and automatically 
def formats=(values)
  if values
    values = values.dup
    values.concat(default_formats) if values.delete "*/*"
    values.uniq!
    unless Template::Types.valid_symbols?(values)
      invalid_values = values - Template::Types.symbols
      raise ArgumentError, "Invalid formats: #{invalid_values.map(&:inspect).join(", ")}"
    end
    if (values.length == 1) && (values[0] == :js)
      values << :html
      @html_fallback_for_js = true
    end
  end
  super(values)
end