class RuboCop::Cop::VariableForce::Variable

So we consider it's used to suppress false positive offenses.
and it means we cannot track the usage of the variable.
when, where and how many times the block would be invoked
Once the variable is captured by a block, we have no idea

For more precise usage check, refer Assignment#used?.
in its entire variable lifetime.
This is a convenient way to check whether the variable is used

def used?
  @captured_by_block || referenced?
end