module RuboCop::Cop::CheckAssignment

def extract_rhs(node)
  if node.call_type?
    node.last_argument
  elsif node.assignment?
    node.expression
  end
end

def on_lvasgn(node)
  check_assignment(node, extract_rhs(node))
end

def on_send(node)
  return unless (rhs = extract_rhs(node))
  check_assignment(node, rhs)
end