class Sass::Tree::Visitors::Perform

def visit_prop(node)
  node.resolved_name = run_interp(node.name)
  # If the node's value is just a variable or similar, we may get a useful
  # source range from evaluating it.
  if node.value.length == 1 && node.value.first.is_a?(Sass::Script::Tree::Node)
    result = node.value.first.perform(@environment)
    node.resolved_value = result.to_s
    node.value_source_range = result.source_range if result.source_range
  elsif node.custom_property?
    node.resolved_value = run_interp_no_strip(node.value)
  else
    node.resolved_value = run_interp(node.value)
  end
  yield
end