The IE-specific `alpha(opacity=@var)`. Less manually resolves the variable here at parse-time. We want to keep the variable around, so we compile this to a function. Less doesn't actually have an `=` operator, but that's okay since it's just getting compiled to Sass anyway.
# File lib/sass/less.rb, line 127 def build(env) Node::Function.new("alpha", [Node::Expression.new([ Node::Keyword.new("opacity"), Node::Operator.new("="), variable.build])]) end