class Opal::Nodes::XStringNode

def self.single_line?(children)

the same line (e.g. because of interpolations)
Check if there's only one child or if they're all part of 
def self.single_line?(children)
  (children.size == 1) || children.none? do |c|
    c.type == :str && c.loc.expression.source.end_with?("\n")
  end
end