class RuboCop::Cop::Lint::AmbiguousAssignment

def on_asgn(node)
  return unless (rhs = rhs(node))
  range = range_between(node.loc.operator.end_pos - 1, rhs.source_range.begin_pos + 1)
  source = range.source
  return unless MISTAKES.key?(source)
  add_offense(range, message: format(MSG, op: MISTAKES[source]))
end