class RuboCop::Cop::Lint::UnderscorePrefixedVariableName

def check_variable(variable)
  return unless variable.should_be_unused?
  return if variable.references.empty?
  return if variable.references.none?(&:explicit?)
  node = variable.declaration_node
  location = if node.type == :match_with_lvasgn
               node.children.first.loc.expression
             else
               node.loc.name
             end
  add_offense(nil, location)
end